feat(auth): add toast feedback for code sending

apps/lib/features/auth/ui/screens/register_verification_screen.dart

@@ -6,7 +6,7 @@ import 'package:go_router/go_router.dart';
 import 'package:formz/formz.dart';
 import '../../../../core/theme/design_tokens.dart';
 import '../../../../shared/widgets/app_button.dart';
-import '../../../../shared/widgets/banner/app_banner.dart';
+import '../../../../shared/widgets/toast/toast.dart';
 import '../../../../shared/widgets/toast/toast_type.dart';
 import '../../presentation/cubits/register_cubit.dart';
 import '../../presentation/bloc/auth_bloc.dart';
@@ -98,6 +98,7 @@ class _RegisterVerificationViewState extends State<RegisterVerificationView> {
 
     if (success && mounted) {
       _startCountdown();
+      Toast.show(context, '验证码已发送', type: ToastType.success);
     }
   }
 
@@ -173,7 +174,12 @@ class _RegisterVerificationViewState extends State<RegisterVerificationView> {
   }
 
   Widget _buildFormContainer() {
-    return BlocBuilder<RegisterCubit, RegisterState>(
+    return BlocConsumer<RegisterCubit, RegisterState>(
+      listener: (context, state) {
+        if (state.errorMessage != null && !state.isStep2Valid) {
+          Toast.show(context, state.errorMessage!, type: ToastType.error);
+        }
+      },
       builder: (context, state) {
         return SizedBox(
           width: 327,
@@ -183,14 +189,6 @@ class _RegisterVerificationViewState extends State<RegisterVerificationView> {
               _buildCodeInput(state),
               const SizedBox(height: 12),
               _buildStepIndicator(),
-              if (state.errorMessage != null)
-                Padding(
-                  padding: const EdgeInsets.only(top: 8),
-                  child: AppBanner(
-                    message: state.errorMessage!,
-                    type: ToastType.error,
-                  ),
-                ),
               const SizedBox(height: 12),
               AppButton(
                 text: '完成注册',