fix(notifications): implement missing onTokenRefreshed stream

Add the missing override for the onTokenRefreshed stream in the NoOpPushNotificationService class. This ensures the class now provides an implementation for all required members of the PushNotificationService interface, including a no-op implementation for the token refresh functionality.

Author: fulleni

lib/notifications/services/no_op_push_notification_service.dart

@@ -42,6 +42,9 @@ class NoOpPushNotificationService extends PushNotificationService {
   Stream<PushNotificationPayload> get onMessageOpenedApp =>
       const Stream.empty();
 
+  @override
+  Stream<String> get onTokenRefreshed => const Stream.empty();
+
   @override
   Future<PushNotificationPayload?> get initialMessage async => null;