fix: 修复proxy_service和account_service中不当的顶层import

- proxy_service.py: 将requests和WhitelistManager改为函数内延迟import，
  避免启动时加载不需要的依赖；移除未使用的get_exit_ip_via_proxy导入
- account_service.py: 移除未使用的func、joinedload、AuditLog、
  user_has_permission顶层导入

web/frontend/src/api/index.ts

@@ -1,22 +1 @@
-import axios from 'axios';
-
-const api = axios.create({
-  baseURL: '/api',
-  timeout: 30000,
-  withCredentials: true, // 携带 httpOnly cookie
-});
-
-// 响应拦截：统一错误处理
-api.interceptors.response.use(
-  (response) => response.data,
-  (error) => {
-    if (error.response?.status === 401) {
-      localStorage.removeItem('user');
-      window.location.href = '/login';
-    }
-    const msg = error.response?.data?.detail || error.message || '请求失败';
-    return Promise.reject(new Error(msg));
-  }
-);
-
-export default api;
+export { default } from './client';