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/CompanyFiles.tsx

@@ -2,7 +2,7 @@ import { useState, useRef } from 'react'
 import { useQuery, useMutation, useQueryClient } from '@tanstack/react-query'
 import { toast } from 'sonner'
 import { Building2, Upload, Trash2, FileText, AlertCircle, Calendar } from 'lucide-react'
-import api from '../lib/api'
+import { companyFilesApi } from '../lib/api-services'
 import Card from '../components/ui/Card'
 import Button from '../components/ui/Button'
 import { Input, Label, Select } from '../components/ui/Input'
@@ -29,13 +29,12 @@ export default function CompanyFiles() {
   const { data: files, isLoading } = useQuery<any[]>({
     queryKey: ['company-files', filterType],
     queryFn: async () => {
-      const res = await api.get('/company-files', { params: filterType ? { fileType: filterType } : {} }) as any
-      return res.data || []
+      return await companyFilesApi.list(filterType ? { fileType: filterType } : {})
     },
   })
 
   const addMutation = useMutation({
-    mutationFn: (data: any) => api.post('/company-files', data),
+    mutationFn: (data: any) => companyFilesApi.add(data),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['company-files'] })
       toast.success('文件上传成功')
@@ -46,7 +45,7 @@ export default function CompanyFiles() {
   })
 
   const deleteMutation = useMutation({
-    mutationFn: (id: string) => api.delete(`/company-files/${id}`),
+    mutationFn: (id: string) => companyFilesApi.remove(id),
     onSuccess: () => {
       queryClient.invalidateQueries({ queryKey: ['company-files'] })
       toast.success('已删除')