Add unit settings, wind particles toggle, and recenter-to-top

- New UnitPrefs: persisted C/F, ft/m, hPa/inHg, kt/mph/kph — defaults to °F
- InstrumentHandler now accepts raw values (knots, metres, hPa, °C) and formats
  via UnitPrefs on every update
- LayerPickerSheet expanded with wind particles toggle and unit chip selectors;
  wrapped in ScrollView to handle the additional height
- MapLayerManager tracks particlesEnabled (persisted); setParticlesEnabled() added
- MainActivity: caches last raw values so refreshUnits() can reformat everything
  instantly when the user changes a unit without waiting for new sensor data
- Recenter button moved to top (below HUD strip) so it's never obscured by the
  bottom sheet or bottom nav
- Unit label TextViews given IDs in HUD and instrument sheet for live updates

https://claude.ai/code/session_01HXPjBsogsJVRwCiekDGkJX

4 files changed, 290 insertions, 81 deletions

diff --git a/android-app/app/src/main/res/layout/activity_main.xml b/android-app/app/src/main/res/layout/activity_main.xml
index 5147506..5943949 100644
--- a/android-app/app/src/main/res/layout/activity_main.xml
+++ b/android-app/app/src/main/res/layout/activity_main.xml
@@ -90,10 +90,10 @@
                 android:visibility="gone"
                 app:cornerRadius="20dp"
                 app:elevation="20dp"
-                app:layout_constraintBottom_toBottomOf="parent"
+                app:layout_constraintTop_toBottomOf="@id/nav_hud"
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintStart_toStartOf="parent"
-                android:layout_marginBottom="24dp" />
+                android:layout_marginTop="8dp" />
 
         </androidx.constraintlayout.widget.ConstraintLayout>
 
diff --git a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
index faec826..03cefb7 100644
--- a/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_instruments_sheet.xml
@@ -56,7 +56,7 @@
                     android:id="@+id/value_tws"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="15.5" />
-                <TextView style="@style/InstrumentUnit" android:text="kts" />
+                <TextView android:id="@+id/unit_tws" style="@style/InstrumentUnit" android:text="kt" />
                 <org.terst.nav.ui.DirectionArrowView
                     android:id="@+id/arrow_tws"
                     android:layout_width="14dp"
@@ -95,7 +95,7 @@
                     android:id="@+id/value_temp"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="18" />
-                <TextView style="@style/InstrumentUnit" android:text="°C" />
+                <TextView android:id="@+id/unit_temp" style="@style/InstrumentUnit" android:text="°F" />
             </LinearLayout>
         </LinearLayout>
 
@@ -123,7 +123,7 @@
                     android:id="@+id/value_baro"
                     style="@style/InstrumentPrimaryValue"
                     tools:text="1013" />
-                <TextView style="@style/InstrumentUnit" android:text="hPa" />
+                <TextView android:id="@+id/unit_baro" style="@style/InstrumentUnit" android:text="hPa" />
             </LinearLayout>
         </LinearLayout>
 
@@ -175,7 +175,7 @@
                     android:id="@+id/value_curr_spd"
                     style="@style/ForecastValue"
                     tools:text="0.8" />
-                <TextView style="@style/ForecastUnit" android:text="kts" />
+                <TextView android:id="@+id/unit_curr_spd" style="@style/ForecastUnit" android:text="kt" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
@@ -214,7 +214,7 @@
                     android:id="@+id/value_wave_ht"
                     style="@style/ForecastValue"
                     tools:text="3.5" />
-                <TextView style="@style/ForecastUnit" android:text="ft" />
+                <TextView android:id="@+id/unit_wave_ht" style="@style/ForecastUnit" android:text="ft" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
@@ -253,7 +253,7 @@
                     android:id="@+id/value_swell_ht"
                     style="@style/ForecastValue"
                     tools:text="5.2" />
-                <TextView style="@style/ForecastUnit" android:text="ft" />
+                <TextView android:id="@+id/unit_swell_ht" style="@style/ForecastUnit" android:text="ft" />
             </LinearLayout>
             <LinearLayout
                 android:layout_width="wrap_content"
diff --git a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
index c424606..fdfbb7a 100644
--- a/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_layer_picker_sheet.xml
@@ -1,104 +1,310 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout
+<ScrollView
     xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:orientation="vertical"
-    android:paddingStart="24dp"
-    android:paddingEnd="24dp"
-    android:paddingBottom="32dp"
     android:background="?attr/colorSurface">
 
-    <View
-        android:layout_width="36dp"
-        android:layout_height="4dp"
-        android:layout_gravity="center_horizontal"
-        android:layout_marginTop="12dp"
-        android:layout_marginBottom="20dp"
-        android:background="@color/md_theme_outline" />
-
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:layout_marginBottom="16dp"
-        android:text="MAP LAYERS"
-        android:textSize="11sp"
-        android:textAllCaps="true"
-        android:letterSpacing="0.12"
-        android:fontFamily="sans-serif-light"
-        android:textColor="@color/instrument_text_secondary" />
-
-    <!-- Base map selection -->
-    <com.google.android.material.chip.ChipGroup
-        android:id="@+id/chip_group_base"
+    <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
-        android:layout_marginBottom="24dp"
-        app:singleSelection="true"
-        app:selectionRequired="true"
-        xmlns:app="http://schemas.android.com/apk/res-auto">
-
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_satellite"
-            style="@style/Widget.Material3.Chip.Filter"
+        android:orientation="vertical"
+        android:paddingStart="24dp"
+        android:paddingEnd="24dp"
+        android:paddingBottom="40dp">
+
+        <View
+            android:layout_width="36dp"
+            android:layout_height="4dp"
+            android:layout_gravity="center_horizontal"
+            android:layout_marginTop="12dp"
+            android:layout_marginBottom="20dp"
+            android:background="@color/md_theme_outline" />
+
+        <!-- ── MAP LAYERS ──────────────────────────────────────────── -->
+
+        <TextView
             android:layout_width="wrap_content"
             android:layout_height="wrap_content"
-            android:text="Satellite" />
+            android:layout_marginBottom="12dp"
+            android:text="MAP LAYERS"
+            android:textSize="11sp"
+            android:textAllCaps="true"
+            android:letterSpacing="0.12"
+            android:fontFamily="sans-serif-light"
+            android:textColor="@color/instrument_text_secondary" />
 
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_charts"
-            style="@style/Widget.Material3.Chip.Filter"
-            android:layout_width="wrap_content"
+        <!-- Base map selection -->
+        <com.google.android.material.chip.ChipGroup
+            android:id="@+id/chip_group_base"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="Charts" />
+            android:layout_marginBottom="20dp"
+            app:singleSelection="true"
+            app:selectionRequired="true">
 
-        <com.google.android.material.chip.Chip
-            android:id="@+id/chip_hybrid"
-            style="@style/Widget.Material3.Chip.Filter"
-            android:layout_width="wrap_content"
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_satellite"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Satellite" />
+
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_charts"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Charts" />
+
+            <com.google.android.material.chip.Chip
+                android:id="@+id/chip_hybrid"
+                style="@style/Widget.Material3.Chip.Filter"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:text="Hybrid" />
+
+        </com.google.android.material.chip.ChipGroup>
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:layout_marginBottom="16dp"
+            android:background="@color/md_theme_surfaceVariant" />
+
+        <!-- Wind overlay toggle -->
+        <LinearLayout
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:text="Hybrid" />
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="12dp">
 
-    </com.google.android.material.chip.ChipGroup>
+            <LinearLayout
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:orientation="vertical">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind overlay"
+                    android:textSize="15sp"
+                    android:textColor="@color/instrument_text_normal" />
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind speed colour map"
+                    android:textSize="12sp"
+                    android:textColor="@color/instrument_text_secondary" />
+            </LinearLayout>
 
-    <!-- Wind divider -->
-    <View
-        android:layout_width="match_parent"
-        android:layout_height="1dp"
-        android:layout_marginBottom="16dp"
-        android:background="@color/md_theme_surfaceVariant" />
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switch_wind"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" />
 
-    <!-- Wind toggle -->
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:orientation="horizontal"
-        android:gravity="center_vertical">
+        </LinearLayout>
 
+        <!-- Wind particles toggle -->
         <LinearLayout
-            android:layout_width="0dp"
+            android:layout_width="match_parent"
             android:layout_height="wrap_content"
-            android:layout_weight="1"
-            android:orientation="vertical">
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="8dp">
+
+            <LinearLayout
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:orientation="vertical">
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Wind particles"
+                    android:textSize="15sp"
+                    android:textColor="@color/instrument_text_normal" />
+                <TextView
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="Animated particle overlay"
+                    android:textSize="12sp"
+                    android:textColor="@color/instrument_text_secondary" />
+            </LinearLayout>
+
+            <com.google.android.material.switchmaterial.SwitchMaterial
+                android:id="@+id/switch_particles"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content" />
+
+        </LinearLayout>
+
+        <!-- ── UNITS ───────────────────────────────────────────────── -->
+
+        <View
+            android:layout_width="match_parent"
+            android:layout_height="1dp"
+            android:layout_marginTop="8dp"
+            android:layout_marginBottom="16dp"
+            android:background="@color/md_theme_surfaceVariant" />
+
+        <TextView
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginBottom="12dp"
+            android:text="UNITS"
+            android:textSize="11sp"
+            android:textAllCaps="true"
+            android:letterSpacing="0.12"
+            android:fontFamily="sans-serif-light"
+            android:textColor="@color/instrument_text_secondary" />
+
+        <!-- Temperature -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
             <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Temperature"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_temp"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:text="Wind overlay"
-                android:textSize="15sp"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_fahrenheit"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="°F" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_celsius"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="°C" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
+
+        <!-- Depth / height -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
+            <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Depth / height"
+                android:textSize="14sp"
                 android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_depth"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_feet"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="ft" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_meters"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="m" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
+
+        <!-- Pressure -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical"
+            android:layout_marginBottom="10dp">
             <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Pressure"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_pressure"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:text="OpenWeatherMap wind speed"
-                android:textSize="12sp"
-                android:textColor="@color/instrument_text_secondary" />
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_hpa"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="hPa" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_inhg"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="inHg" />
+            </com.google.android.material.chip.ChipGroup>
         </LinearLayout>
 
-        <com.google.android.material.switchmaterial.SwitchMaterial
-            android:id="@+id/switch_wind"
-            android:layout_width="wrap_content"
-            android:layout_height="wrap_content" />
+        <!-- Speed -->
+        <LinearLayout
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:orientation="horizontal"
+            android:gravity="center_vertical">
+            <TextView
+                android:layout_width="0dp"
+                android:layout_height="wrap_content"
+                android:layout_weight="1"
+                android:text="Speed"
+                android:textSize="14sp"
+                android:textColor="@color/instrument_text_normal" />
+            <com.google.android.material.chip.ChipGroup
+                android:id="@+id/chip_group_speed"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                app:singleSelection="true"
+                app:selectionRequired="true">
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_knots"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="kt" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_mph"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="mph" />
+                <com.google.android.material.chip.Chip
+                    android:id="@+id/chip_kph"
+                    style="@style/Widget.Material3.Chip.Filter"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:text="kph" />
+            </com.google.android.material.chip.ChipGroup>
+        </LinearLayout>
 
     </LinearLayout>
-
-</LinearLayout>
+</ScrollView>
diff --git a/android-app/app/src/main/res/layout/layout_nav_hud.xml b/android-app/app/src/main/res/layout/layout_nav_hud.xml
index 4623bb1..90119fa 100644
--- a/android-app/app/src/main/res/layout/layout_nav_hud.xml
+++ b/android-app/app/src/main/res/layout/layout_nav_hud.xml
@@ -39,6 +39,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="7.1" />
             <TextView
+                android:id="@+id/unit_hud_sog"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="kt"
@@ -110,6 +111,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="6.8" />
             <TextView
+                android:id="@+id/unit_hud_bsp"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="kt"
@@ -149,6 +151,7 @@
                 android:fontFamily="sans-serif-medium"
                 tools:text="42.0" />
             <TextView
+                android:id="@+id/unit_hud_depth"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="ft"