테넌트 접근 제한 안내화면 개선

userfront/lib/features/auth/domain/consent_error_routing.dart

@@ -0,0 +1,5 @@
+import 'package:userfront/core/services/auth_proxy_service.dart';
+
+bool shouldRouteConsentErrorToErrorScreen(Object error) {
+  return error is AuthProxyException && error.errorCode == 'tenant_not_allowed';
+}