권한 동의 거부 api 호출 함수 추가

userfront/lib/core/services/auth_proxy_service.dart

@@ -261,6 +261,26 @@ class AuthProxyService {
     }
   }
 
+  static Future<Map<String, dynamic>> rejectConsent(String consentChallenge) async {
+    final url = Uri.parse('$_baseUrl/api/v1/auth/consent/reject');
+    final body = <String, dynamic>{
+      'consent_challenge': consentChallenge,
+    };
+
+    final response = await http.post(
+      url,
+      headers: {'Content-Type': 'application/json'},
+      body: jsonEncode(body),
+    );
+
+    if (response.statusCode == 200) {
+      return jsonDecode(response.body);
+    } else {
+      final errorBody = jsonDecode(response.body);
+      throw Exception(errorBody['error'] ?? 'Failed to reject consent');
+    }
+  }
+
   static Future<Map<String, dynamic>> acceptOidcLogin(
     String loginChallenge, {
     String? token,