style(userfront): format dart files to fix ci pipeline

userfront/lib/core/services/auth_proxy_service.dart

@@ -1072,7 +1072,8 @@ class AuthProxyService {
         }
       } catch (e) {
         // Fallback if the body isn't valid JSON (e.g., an HTML error page)
-        errorMessage = 'Server error (${response.statusCode}): ${response.body.isNotEmpty ? response.body.substring(0, response.body.length > 100 ? 100 : response.body.length) : "Unknown error"}';
+        errorMessage =
+            'Server error (${response.statusCode}): ${response.body.isNotEmpty ? response.body.substring(0, response.body.length > 100 ? 100 : response.body.length) : "Unknown error"}';
       }
       throw Exception(errorMessage);
     }