phase3: nullfix.py batch script — bang/late/param-nullable

Automated null-safety fixes driven by dart analyze (no corruption):
- unchecked_use_of_nullable_value: insert '!' on receiver (property/method/[]/op)
- not_initialized field/var: mark 'late'
- missing_default_value_for_parameter: nullable param
Errors: 2374(peak) -> 907

lib/widgets/general/payment_verification_code_dialog.dart

@@ -33,8 +33,8 @@ class PaymentVerificationCodeDialogState extends State<PaymentVerificationCodeDi
   String getCodeText = '';
   String paymentCodeEncrypt = '';
 
-  String verifyMethod;
-  String verifyName;
+  late String verifyMethod;
+  late String verifyName;
 
   final TextEditingController _pinPutController = TextEditingController();
   final FocusNode _pinPutFocusNode = FocusNode();