/**
 * CORS 中间件
 */
export const corsMiddleware = (event) => {
  // 设置 CORS 头
  event.res.headers.set('Access-Control-Allow-Origin', '*');
  event.res.headers.set('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS');
  event.res.headers.set('Access-Control-Allow-Headers', 'Content-Type, Authorization');
  event.res.headers.set('Access-Control-Max-Age', '86400');

  // 处理预检请求
  if (event.method === 'OPTIONS') {
    return '';
  }
};