add secure storage (not working)

lib/services/tokenStorageService.dart

@@ -0,0 +1,36 @@
+import 'package:flutter_secure_storage/flutter_secure_storage.dart';
+
+class TokenStorageService {
+  // Singleton pattern (optional but usually handy for services)
+  TokenStorageService._internal();
+
+  static final TokenStorageService _instance = TokenStorageService._internal();
+
+  factory TokenStorageService() => _instance;
+
+  static const _tokenKey = 'auth_token';
+
+  // Use const constructor for secure storage
+  final FlutterSecureStorage _storage = const FlutterSecureStorage();
+
+  /// Save or update the token
+  Future<void> setToken(String token) async {
+    await _storage.write(key: _tokenKey, value: token);
+  }
+
+  /// Retrieve the stored token (null if none)
+  Future<String?> getToken() async {
+    return _storage.read(key: _tokenKey);
+  }
+
+  /// Delete the token
+  Future<void> clearToken() async {
+    await _storage.delete(key: _tokenKey);
+  }
+
+  /// Optional: check quickly if a token exists
+  Future<bool> hasToken() async {
+    final token = await getToken();
+    return token != null && token.isNotEmpty;
+  }
+}