feat: refactor UI to BottomNavigationView with Safety and Doc fragments

Replace FAB-based navigation with a 4-tab BottomNavigationView (Map,
Instruments, Log, Safety). Instruments use a collapsible bottom sheet;
Log and Safety display as full-screen overlay fragments.

- Add SafetyFragment with MOB and Anchor Watch controls
- Add DocFragment for in-app markdown help (Markwon: core, tables, images)
- Add layout_instruments_sheet with 3x3 instrument grid and PolarDiagramView
- Add fragment_safety and fragment_doc layouts
- Add vector drawables: ic_map, ic_instruments, ic_log, ic_safety, ic_close
- Update activity_main.xml to CoordinatorLayout with bottom sheet + overlay
- Fix: set isHideable=true before STATE_HIDDEN to avoid silent no-op from
  behavior_hideable=false default; restore false on Map/Instruments tabs

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

1 files changed, 36 insertions, 0 deletions

diff --git a/android-app/app/src/main/res/layout/fragment_doc.xml b/android-app/app/src/main/res/layout/fragment_doc.xml
new file mode 100644
index 0000000..c5ecb4f
--- /dev/null
+++ b/android-app/app/src/main/res/layout/fragment_doc.xml
@@ -0,0 +1,36 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.coordinatorlayout.widget.CoordinatorLayout 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="match_parent"
+    android:background="?attr/colorSurface">
+
+    <com.google.android.material.appbar.AppBarLayout
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+        <com.google.android.material.appbar.MaterialToolbar
+            android:id="@+id/toolbar"
+            android:layout_width="match_parent"
+            android:layout_height="?attr/actionBarSize"
+            app:title="Help" />
+
+    </com.google.android.material.appbar.AppBarLayout>
+
+    <androidx.core.widget.NestedScrollView
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        app:layout_behavior="@string/appbar_scrolling_view_behavior">
+
+        <TextView
+            android:id="@+id/doc_text"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="24dp"
+            android:textColor="?attr/colorOnSurface"
+            android:textSize="16sp"
+            android:lineSpacingExtra="4dp" />
+
+    </androidx.core.widget.NestedScrollView>
+
+</androidx.coordinatorlayout.widget.CoordinatorLayout>