📊 Analytics: restore UI events, Firebase Analytics on iOS

[ngapp-dev]

Summary

🐛 Analytics UI events were never sent

• Since the KMP migration nothing provided LocalAnalyticsHelper, so every event logged from the UI (screen views, opened stations, news and careers, language changes) went to its NoOpAnalyticsHelper default. Only data-layer and sync events reached Firebase.
• MetanMobileApp now provides the Koin AnalyticsHelper at the root, as the old MainActivity did.
• Restored the Cabinet screen view, lost in the migration. All other pre-KMP analytics call sites were checked and are present (the old Station detail screen logged its view twice; it now logs once).

✨ Firebase Analytics on iOS

• iOS logged nothing (NoOpAnalyticsHelper). The shared code's events now go to Firebase Analytics, the same project as Android, so both platforms report the same events.
• core:analytics: AnalyticsBridge (implemented in Swift) and BridgedAnalyticsHelper, which truncates params to Firebase's limits like Android's FirebaseAnalyticsHelper; exported in the framework.
• initSharedKoin takes the bridge; FirebaseAnalyticsBridge and FirebaseApp.configure() in MetanMobileApp.swift.
• Xcode: firebase-ios-sdk (FirebaseAnalytics) on the app target.
• Sync events (network_sync_started / _successful / _failed) on iOS too: the helpers move to sync:work's commonMain; IosSyncManager (per attempt) and the BGTaskScheduler refresh log them, like Android's SyncWorker.

⚙️ CI: iOS on the xcode-27 image

• macos-latest only has Xcode 26.x, so the iOS job failed with "Could not find Xcode version that satisfied version spec: '27'". It now runs on the xcode-27 preview image ([macOS] Xcode 27 is now available as a public preview actions/runner-images#14404); switch back once macos-latest ships Xcode 27.

Review notes

• GoogleService-Info.plist is gitignored like google-services.json: put it in iosApp/MetanMobileApp/ to build the app. CI doesn't build the app target, so it's unaffected.
• Verified: Android emulator logs screen_view with screen names (HomeScreen, StationDetailScreen); the iOS simulator registers with Firebase Installations and its local measurement DB counts screen_view growing while navigating and network_sync_started / network_sync_successful after launch, with the upload queue emptying.
• Android debug builds still get "Firebase Installations Service is unavailable": the API key is restricted in Google Cloud Credentials to com.ngapp.metanmobile only (HTTP 403 API_KEY_ANDROID_APP_BLOCKED). Release is fine. Fix in the console by adding com.ngapp.metanmobile.debug + the debug SHA-1 to the key's Android restrictions.
• Tests: BridgedAnalyticsHelper on the JVM and the iOS simulator.