Fix #15: PCI-DSS compliance - remove persistent CVV storage from Flutter apps

siro_rider/lib/main.dart

@@ -15,6 +15,7 @@ import 'package:get_storage/get_storage.dart';
 import 'package:flutter/services.dart';
 import 'package:wakelock_plus/wakelock_plus.dart';
 import 'constant/info.dart';
+import 'constant/box_name.dart';
 import 'controller/home/ios_live_activity_service.dart';
 import 'controller/local/local_controller.dart';
 import 'controller/local/translations.dart';
@@ -43,6 +44,8 @@ void main() {
     // These must complete before the UI can be built.
     WidgetsFlutterBinding.ensureInitialized();
     await GetStorage.init();
+    // Purge any previously stored CVV (PCI-DSS compliance)
+    await storage.delete(key: BoxName.cvvCode);
     WakelockPlus.enable();
     if (Platform.isAndroid || Platform.isIOS) {
       await Firebase.initializeApp(