fix login error

frontend/src/services/api.ts

@@ -38,7 +38,7 @@ class ApiService {
     // Response interceptor: Handle errors
     this.axiosInstance.interceptors.response.use(
       (response) => response,
-      (error: AxiosError) => {
+      async (error: AxiosError) => {
         if (error.response?.status === 401) {
           // Clear tokens and redirect to login
           console.warn('Unauthorized request, redirecting to login');
@@ -46,6 +46,22 @@ class ApiService {
           removeUser();
           window.location.href = '/login';
         }
+
+        // Retry on 429 (Too Many Requests) with exponential backoff
+        if (error.response?.status === 429 && error.config) {
+          const config = error.config as AxiosRequestConfig & { _retryCount?: number };
+          const retryCount = config._retryCount || 0;
+          const maxRetries = 3;
+
+          if (retryCount < maxRetries) {
+            config._retryCount = retryCount + 1;
+            const delay = Math.pow(2, retryCount) * 1000; // 1s, 2s, 4s
+            console.warn(`Rate limited (429). Retrying in ${delay}ms (attempt ${retryCount + 1}/${maxRetries})...`);
+            await new Promise((resolve) => setTimeout(resolve, delay));
+            return this.axiosInstance.request(config);
+          }
+        }
+
         return Promise.reject(this.handleError(error));
       }
     );