feat: Implement Firebase push notifications with support for flavor-specific configurations.

lib/features/auth/presentation/providers/auth_provider.dart

@@ -1,6 +1,7 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:real_estate_mobile/core/network/api_client.dart';
 import 'package:real_estate_mobile/core/network/api_exceptions.dart';
+import 'package:real_estate_mobile/core/services/push_notification_service.dart';
 import 'package:real_estate_mobile/core/storage/secure_storage.dart';
 import 'package:real_estate_mobile/features/auth/data/auth_repository.dart';
 import 'package:real_estate_mobile/features/auth/data/models/register_request.dart';
@@ -76,6 +77,8 @@ class AuthNotifier extends StateNotifier<AuthState> {
         status: AuthStatus.authenticated,
         user: user,
       );
+      // Register for push notifications after auth confirmed
+      _initPushNotifications();
     } catch (_) {
       // Token is invalid/expired — clear and show login
       await SecureStorage.clearTokens();
@@ -85,6 +88,8 @@ class AuthNotifier extends StateNotifier<AuthState> {
 
   Future<void> logout() async {
     state = state.copyWith(status: AuthStatus.loading);
+    // Unregister FCM token before clearing auth
+    await PushNotificationService().unregister();
     await _repository.logout();
     state = const AuthState();
   }
@@ -117,6 +122,7 @@ class AuthNotifier extends StateNotifier<AuthState> {
         status: AuthStatus.authenticated,
         user: result['user'] as UserModel,
       );
+      _initPushNotifications();
     } on ApiException catch (e) {
       state = state.copyWith(
         status: AuthStatus.error,
@@ -166,6 +172,7 @@ class AuthNotifier extends StateNotifier<AuthState> {
         user: user,
         registeredEmail: email,
       );
+      _initPushNotifications();
     } on ApiException catch (e) {
       state = state.copyWith(
         status: AuthStatus.error,
@@ -182,6 +189,11 @@ class AuthNotifier extends StateNotifier<AuthState> {
     }
   }
 
+  void _initPushNotifications() {
+    final push = PushNotificationService();
+    push.initialize().then((_) => push.registerAfterLogin());
+  }
+
   void reset() {
     state = const AuthState();
   }