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

frontend/src/pages/Termination.tsx

@@ -6,6 +6,7 @@ import { Stepper } from '../components/ui/Stepper'
 import { InlineAlert } from '../components/ui/InlineAlert'
 import jsPDF from 'jspdf'
 import api from '../lib/api'
+import { rosterApi } from '../lib/api-services'
 import { useAuthStore } from '../store/authStore'
 import Card from '../components/ui/Card'
 import Button from '../components/ui/Button'
@@ -217,10 +218,10 @@ export default function Termination() {
   const [draftPage, setDraftPage] = useState(1)
   const [draftPageSize, setDraftPageSize] = useState(20)
 
-  const { data: employees } = useQuery<RosterEmployee[]>({
+  const { data: employees } = useQuery<any[]>({
     queryKey: ['roster-for-termination'],
     queryFn: async () => {
-      const res = await api.get('/roster') as any
+      const res = await rosterApi.list({ pageSize: 999 })
       return res.data
     },
   })
@@ -229,10 +230,7 @@ export default function Termination() {
 
   const { data: departmentList } = useQuery<string[]>({
     queryKey: ['roster-departments'],
-    queryFn: async () => {
-      const res = await api.get('/roster/departments') as any
-      return res.data || []
-    },
+    queryFn: () => rosterApi.departments(),
   })
 
   const { data: profile } = useQuery<EmployeeProfile>({