feat: add token check to notification refresh and methods for controlling notification polling.

lib/features/notifications/presentation/providers/notification_provider.dart

@@ -1,6 +1,7 @@
 import 'dart:async';
 
 import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:real_estate_mobile/core/storage/secure_storage.dart';
 import 'package:real_estate_mobile/features/notifications/data/models/notification_model.dart';
 import 'package:real_estate_mobile/features/notifications/data/notification_repository.dart';
 
@@ -20,6 +21,12 @@ class UnreadCountNotifier extends StateNotifier<int> {
   }
 
   Future<void> refresh() async {
+    // Skip if no token (logged out) — prevents 401 errors
+    final token = await SecureStorage.getAccessToken();
+    if (token == null) {
+      if (mounted) state = 0;
+      return;
+    }
     try {
       final count = await _repo.getUnreadCount();
       if (mounted) state = count;
@@ -28,6 +35,20 @@ class UnreadCountNotifier extends StateNotifier<int> {
     }
   }
 
+  /// Stop polling (call on logout).
+  void stopPolling() {
+    _timer?.cancel();
+    _timer = null;
+    if (mounted) state = 0;
+  }
+
+  /// Restart polling (call on login).
+  void startPolling() {
+    _timer?.cancel();
+    refresh();
+    _timer = Timer.periodic(const Duration(seconds: 30), (_) => refresh());
+  }
+
   @override
   void dispose() {
     _timer?.cancel();