拆分接单平台超长文件，按域组织代码

- worker-platform-service.ts (2733行) 拆为 worker-service/admin-service/mappers + index 聚合
- worker-platform-repo.ts (2456行) 拆为 repositories/worker-platform/ 目录（types/shared/worker-repo/work-order-repo）
- AdminWorkerPlatformPage.tsx (2784行) 拆为主页面 + panels/ 目录（7 个面板文件）
- 引用方统一改指向 index 聚合，行为不变

apps/backend/src/routes/worker.ts

@@ -20,7 +20,7 @@ import {
   logoutWorkerSession,
   registerWorker,
   submitWorkerOrderAcceptance,
-} from '../services/worker-platform/worker-platform-service.js'
+} from '../services/worker-platform/index.js'
 import { buildNotFoundPayload, createRouteHandler } from '../utils/http.js'
 import {
   extractOptionalWorkerBearerToken,