refactor: API口径统一 — 统计函数/员工列表/前端服务层

后端:
- /dashboard/compliance-score 改用 getHealthCheck，与体检诊断同口径
- 新增 /employees/list 端点（不分页，供各页面下拉选择）
- /employees/all-lite 增加 position 字段和 status 筛选参数
- getHealthCheck 未签合同改为查无合同记录的员工（非UNSIGNED类型）

前端:
- 新建 lib/api-services.ts 统一 API 服务层
- employeeApi/rosterApi/dashboardApi/attendanceApi 统一封装
- 6个页面迁移到统一 API 调用:
  - Attendance: employeeApi.list + rosterApi.departments
  - Termination: rosterApi.list + rosterApi.departments
  - Money: rosterApi.list + rosterApi.departments
  - PortalQRModal: employeeApi.list
  - AIAssistant: 3处 employeeApi.list 替代 /roster?pageSize=999
  - Contracts: rosterApi.departments
  - Dashboard: rosterApi.expiringContracts + dashboardApi.healthCheck/workforceStats

backend/src/routes/dashboard.routes.ts

@@ -99,10 +99,10 @@ router.get('/cost-analysis', authMiddleware, async (req: AuthRequest, res: Respo
   }
 })
 
-// 合规健康度评分 + AI 建议卡片流
+// 合规健康度评分 — 已统一为 getHealthCheck 口径
 router.get('/compliance-score', authMiddleware, async (req: AuthRequest, res: Response, next: NextFunction) => {
   try {
-    const data = await getComplianceScore(req.user!.orgId)
+    const data = await getHealthCheck(req.user!.orgId)
     res.json({ success: true, data })
   } catch (err) {
     next(err)