rebrand app from Bocken Fitness to Bocken, track Android project

- Manifest: name/short_name → "Bocken", start_url → "/"
- Tauri: productName → "Bocken", identifier → org.bocken.app, url → "/"
- Cargo: package → bocken, lib → bocken_lib
- Page titles: "- Fitness" → "- Bocken" across all fitness routes
- Build script: auto-regenerate android project on identifier change
- Regenerate app icon from website favicon
- Track Android project source in git (ignore only build output/caches)
- Add native GPS foreground service and AndroidBridge for background
  location tracking (LocationForegroundService, AndroidBridge.kt)
- Add ACCESS_BACKGROUND_LOCATION permission for screen-off GPS

.gitignore

@@ -10,6 +10,13 @@ node_modules
 !.env.example
 vite.config.js.timestamp-*
 vite.config.ts.timestamp-*
-src-tauri/gen/
 src-tauri/target/
 src-tauri/*.keystore
+# Android: ignore build output and caches, track source files
+src-tauri/gen/android/.gradle/
+src-tauri/gen/android/app/build/
+src-tauri/gen/android/buildSrc/.gradle/
+src-tauri/gen/android/buildSrc/build/
+src-tauri/gen/android/gradle/
+src-tauri/gen/android/gradlew
+src-tauri/gen/android/gradlew.bat