e worker 离线

Service Worker 离线回退与路由降级策略

`title: Service Worker 离线回退与路由降级策略``categories: Web 开发/前端/数据管理``keywords: Service Worker,离线回退,路由降级,占位,缓存``description: 为文档与接口设计离线回退与路由降级策略,提供占位与队列入库,保