update

lib/core/services/biometric_service.dart

@@ -0,0 +1,37 @@
+import 'package:local_auth/local_auth.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+class BiometricService {
+  static final _auth = LocalAuthentication();
+  static const _key = 'biometric_enabled';
+
+  static Future<bool> isAvailable() async {
+    final canCheck = await _auth.canCheckBiometrics;
+    final isSupported = await _auth.isDeviceSupported();
+    return canCheck && isSupported;
+  }
+
+  static Future<bool> isEnabled() async {
+    final prefs = await SharedPreferences.getInstance();
+    return prefs.getBool(_key) ?? false;
+  }
+
+  static Future<void> setEnabled(bool value) async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setBool(_key, value);
+  }
+
+  static Future<bool> authenticate() async {
+    try {
+      return await _auth.authenticate(
+        localizedReason: 'Confirm your identity to open Casha',
+        options: const AuthenticationOptions(
+          biometricOnly: false,
+          stickyAuth: true,
+        ),
+      );
+    } catch (_) {
+      return false;
+    }
+  }
+}