fix: saved tracks browser, GPX import persistence

Saved tracks browser:
- TrackDetailSheet converted from BottomSheetDialogFragment to Fragment so
  it fills the overlay instead of floating over the map
- Adapter tap pushes detail fragment onto the back stack; back button returns
  to the list naturally via popBackStack()
- SavedTracksFragment back button calls hideOverlays() (made internal) to
  close the overlay and return to the map
- Layout updated to full-screen: header with back button, RecyclerView fills
  remaining space via layout_weight instead of fixed 300dp

GPX import persistence:
- TrackRepository.importTrack() saves parsed points to Documents/Nav/ via
  TrackStorage (URI is persisted to SharedPreferences) and adds to
  in-memory list
- MainViewModel.addImportedTrack() now calls importTrack() so files opened
  via the GPX handler load on future launches

https://claude.ai/code/session_01DNjbYxiC1cco83dArNGW3G

1 files changed, 36 insertions, 22 deletions

diff --git a/android-app/app/src/main/res/layout/layout_track_detail_sheet.xml b/android-app/app/src/main/res/layout/layout_track_detail_sheet.xml
index 9b2eb30..6a2ba50 100644
--- a/android-app/app/src/main/res/layout/layout_track_detail_sheet.xml
+++ b/android-app/app/src/main/res/layout/layout_track_detail_sheet.xml
@@ -2,34 +2,47 @@
 <LinearLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="wrap_content"
+    android:layout_height="match_parent"
     android:orientation="vertical"
-    android:paddingBottom="16dp">
+    android:background="?attr/colorSurface">
 
-    <!-- drag handle -->
-    <View
-        android:layout_width="40dp"
-        android:layout_height="4dp"
-        android:layout_gravity="center_horizontal"
-        android:layout_marginTop="8dp"
-        android:layout_marginBottom="8dp"
-        android:background="#BDBDBD" />
-
-    <TextView
-        android:id="@+id/detail_title"
+    <!-- Header -->
+    <LinearLayout
         android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:paddingHorizontal="20dp"
-        android:paddingBottom="12dp"
-        android:textSize="17sp"
-        android:textStyle="bold" />
+        android:layout_height="56dp"
+        android:orientation="horizontal"
+        android:gravity="center_vertical"
+        android:paddingStart="8dp"
+        android:paddingEnd="16dp"
+        android:elevation="4dp"
+        android:background="?attr/colorSurface">
 
-    <!-- stats row: distance · duration · max · avg -->
+        <ImageButton
+            android:id="@+id/btn_back"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:src="@drawable/ic_back"
+            android:background="?attr/selectableItemBackgroundBorderless"
+            android:contentDescription="Back" />
+
+        <TextView
+            android:id="@+id/detail_title"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:textSize="17sp"
+            android:textStyle="bold"
+            android:layout_marginStart="4dp" />
+
+    </LinearLayout>
+
+    <!-- Stats row: distance · duration · max · avg -->
     <LinearLayout
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
         android:orientation="horizontal"
         android:paddingHorizontal="12dp"
+        android:paddingTop="12dp"
         android:paddingBottom="12dp">
 
         <LinearLayout android:layout_width="0dp" android:layout_height="wrap_content"
@@ -69,7 +82,6 @@
     <View android:layout_width="match_parent" android:layout_height="1dp"
         android:background="?attr/colorOutlineVariant" android:layout_marginHorizontal="16dp" />
 
-    <!-- event log -->
     <TextView
         android:layout_width="match_parent"
         android:layout_height="wrap_content"
@@ -85,7 +97,9 @@
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/rv_log_entries"
         android:layout_width="match_parent"
-        android:layout_height="300dp"
-        android:nestedScrollingEnabled="true" />
+        android:layout_height="0dp"
+        android:layout_weight="1"
+        android:clipToPadding="false"
+        android:paddingBottom="24dp" />
 
 </LinearLayout>