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

src-tauri/gen/android/buildSrc/build.gradle.kts

@@ -0,0 +1,23 @@
+plugins {
+    `kotlin-dsl`
+}
+
+gradlePlugin {
+    plugins {
+        create("pluginsForCoolKids") {
+            id = "rust"
+            implementationClass = "RustPlugin"
+        }
+    }
+}
+
+repositories {
+    google()
+    mavenCentral()
+}
+
+dependencies {
+    compileOnly(gradleApi())
+    implementation("com.android.tools.build:gradle:8.11.0")
+}
+