feat(ui): implement edge-to-edge support and improve splash transition

- Enable edge-to-edge display in `MainActivity` and handle window insets in `PlayerFragment`.
- Add a fade-out animation when hiding the loading overlay.
- Sync player state with the controller during setup and reset playing state in preferences on service destruction.
- Simplify splash screen drawable and update background color attributes in layout.
- Remove manual navigation bar color overrides.

app/src/main/res/layout/activity_main.xml

@@ -4,6 +4,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
+    android:background="?android:attr/colorBackground"
     android:fitsSystemWindows="true"
     tools:context=".MainActivity">