feat: move Layers from bottom nav to dedicated FAB

Replaces the nav_layers bottom nav item with a mini FloatingActionButton
anchored below the HUD, giving layers access without occupying a nav slot.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

3 files changed, 19 insertions, 9 deletions

diff --git a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
index eaab575..da96e98 100644
--- a/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
+++ b/android-app/app/src/main/kotlin/org/terst/nav/MainActivity.kt
@@ -64,6 +64,7 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private lateinit var bottomSheetBehavior: BottomSheetBehavior<View>
     private lateinit var fragmentContainer: FrameLayout
     private lateinit var fabRecordTrack: FloatingActionButton
+    private lateinit var fabLayers: FloatingActionButton
     private lateinit var fabRecenter: MaterialButton
     private lateinit var bottomSheet: CardView
     private lateinit var bottomNav: BottomNavigationView
@@ -126,7 +127,11 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
     private fun initializeUI() {
         fragmentContainer = findViewById(R.id.fragment_container)
         fabRecordTrack = findViewById(R.id.fab_record_track)
+        fabLayers = findViewById(R.id.fab_layers)
         fabRecenter = findViewById(R.id.fab_recenter)
+        fabLayers.setOnClickListener {
+            buildLayerPickerSheet().show(supportFragmentManager, "layer_picker")
+        }
         bottomSheet = findViewById(R.id.instrument_bottom_sheet)
         bottomNav = findViewById(R.id.bottom_navigation)
         mapCrosshair = findViewById(R.id.map_crosshair)
@@ -292,11 +297,6 @@ class MainActivity : AppCompatActivity(), SafetyFragment.SafetyListener {
                     bottomSheetBehavior.state = BottomSheetBehavior.STATE_COLLAPSED
                     true
                 }
-                R.id.nav_layers -> {
-                    buildLayerPickerSheet().show(supportFragmentManager, "layer_picker")
-                    bottomNav.post { bottomNav.selectedItemId = R.id.nav_map }
-                    true
-                }
                 R.id.nav_log -> {
                     showOverlay(VoiceLogFragment())
                     bottomSheetBehavior.isHideable = true
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 4150b2e..6832daa 100644
--- a/android-app/app/src/main/res/layout/activity_main.xml
+++ b/android-app/app/src/main/res/layout/activity_main.xml
@@ -39,6 +39,20 @@
                 app:layout_constraintStart_toStartOf="parent"
                 app:layout_constraintEnd_toEndOf="parent" />
 
+            <!-- Layers FAB — map layer picker -->
+            <com.google.android.material.floatingactionbutton.FloatingActionButton
+                android:id="@+id/fab_layers"
+                android:layout_width="wrap_content"
+                android:layout_height="wrap_content"
+                android:layout_marginTop="8dp"
+                android:layout_marginEnd="12dp"
+                android:contentDescription="Layers"
+                app:srcCompat="@drawable/ic_layers"
+                app:fabSize="mini"
+                app:elevation="8dp"
+                app:layout_constraintTop_toBottomOf="@id/nav_hud"
+                app:layout_constraintEnd_toEndOf="parent" />
+
             <!-- Crosshair — visible when not following (panning) -->
             <ImageView
                 android:id="@+id/map_crosshair"
diff --git a/android-app/app/src/main/res/menu/bottom_nav_menu.xml b/android-app/app/src/main/res/menu/bottom_nav_menu.xml
index 5c6de7e..4bbf8b6 100644
--- a/android-app/app/src/main/res/menu/bottom_nav_menu.xml
+++ b/android-app/app/src/main/res/menu/bottom_nav_menu.xml
@@ -5,10 +5,6 @@
         android:icon="@drawable/ic_map"
         android:title="Map" />
     <item
-        android:id="@+id/nav_layers"
-        android:icon="@drawable/ic_layers"
-        android:title="Layers" />
-    <item
         android:id="@+id/nav_log"
         android:icon="@drawable/ic_log"
         android:title="Log" />