refactor: 全量迁移前端 API 调用到统一 api-services 服务层

- 新建 api-services-raw.ts 导出原始 axios 方法供特殊端点使用
- 完成 api-services.ts 全领域覆盖（auth/employee/roster/dashboard/attendance/payroll/socialInsurance/commercialInsurance/termination/policies/evidence/audit/calendar/companyFiles/notifications/settings/ai/platform/portal/survey/search）
- 迁移所有 47+ 页面文件：pages/、pages/roster/、pages/portal/、pages/platform/、pages/auth/、pages/dashboard/、pages/compliance/
- 移除所有直接 import api from '../../lib/api' 引用
- 修复 Termination.tsx / WorkProcess.tsx 中 string|null 类型错误
- 修复 SocialInsurance.tsx 中 api-services-raw delete 导入名
- 修复 PlatformLogin.tsx 变量遮蔽问题
- tsc --noEmit 零错误，vite build 成功

frontend/src/pages/dashboard/TaskCenter.tsx

@@ -5,7 +5,7 @@
 import { useQuery } from '@tanstack/react-query'
 import { Link } from 'react-router-dom'
 import { AlertCircle, Layers, FileText, Heart, ArrowRight, ListTodo } from 'lucide-react'
-import api from '../../lib/api'
+import { dashboardApi } from '../../lib/api-services'
 import { InlineAlert } from '../../components/ui/InlineAlert'
 
 interface NextAction {
@@ -44,8 +44,7 @@ export function TaskCenter() {
   const { data, isLoading } = useQuery<{ actions: ActionGroup[]; totalCount: number }>({
     queryKey: ['next-actions'],
     queryFn: async () => {
-      const res = await api.get('/dashboard/workspace/next-actions') as any
-      return res.data
+      return await dashboardApi.nextActions()
     },
     staleTime: 60_000,
   })