feat(app): 班级码验证前后端联调 — AuthBloc接入API + 错误计数锁定UI

app/lib/features/auth/views/role_selection_page.dart

@@ -11,6 +11,7 @@ import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:go_router/go_router.dart';
 
 import '../../../core/constants/design_tokens.dart';
+import '../../../core/theme/app_radius.dart';
 import '../../../data/models/user.dart';
 import '../bloc/auth_bloc.dart';
 
@@ -146,11 +147,11 @@ class _RoleCardWidget extends StatelessWidget {
       color: Colors.transparent,
       child: InkWell(
         onTap: onTap,
-        borderRadius: BorderRadius.circular(22),
+        borderRadius: AppRadius.lgBorder,
         child: Ink(
           decoration: BoxDecoration(
             color: role.color.withValues(alpha: 0.12),
-            borderRadius: BorderRadius.circular(22),
+            borderRadius: AppRadius.lgBorder,
             border: Border.all(
               color: role.color.withValues(alpha: 0.3),
               width: 2,