feat: Enhance background geofence functionality with notifications and localization support

apps/mobile/packages/core/lib/src/services/device/notification/notification_service.dart

@@ -12,8 +12,14 @@ class NotificationService extends BaseDeviceService {
   /// The underlying notification plugin instance.
   final FlutterLocalNotificationsPlugin _plugin;
 
+  /// Whether [initialize] has already been called.
+  bool _initialized = false;
+
   /// Initializes notification channels and requests permissions.
+  ///
+  /// Safe to call multiple times — subsequent calls are no-ops.
   Future<void> initialize() async {
+    if (_initialized) return;
     return action(() async {
       const AndroidInitializationSettings androidSettings = AndroidInitializationSettings(
         '@mipmap/ic_launcher',
@@ -28,15 +34,22 @@ class NotificationService extends BaseDeviceService {
         iOS: iosSettings,
       );
       await _plugin.initialize(settings: settings);
+      _initialized = true;
     });
   }
 
+  /// Ensures the plugin is initialized before use.
+  Future<void> _ensureInitialized() async {
+    if (!_initialized) await initialize();
+  }
+
   /// Displays a local notification with the given [title] and [body].
   Future<void> showNotification({
     required String title,
     required String body,
     int id = 0,
   }) async {
+    await _ensureInitialized();
     return action(() async {
       const AndroidNotificationDetails androidDetails = AndroidNotificationDetails(
         'krow_geofence',