refactor(frontend): services/api 迁至 src/api，http 迁至 utils/request

对齐 Vue 后台惯例：
- src/api/          域 API（原 services/api）
- src/utils/request.ts  HTTP 封装（原 services/http.ts）
- src/utils/export.ts  客户端导出工具
- src/utils/index.ts   工具统一出口

全局导入改为 @/api 与 @/utils/request，tsc + build 通过。

frontend/src/components/system/CredentialManager.tsx

@@ -16,7 +16,7 @@ import {
 import {
   Plus, Trash2, Edit3, Key, Globe, Shield, Eye, EyeOff, RefreshCw,
 } from 'lucide-react';
-import { credentialApi } from '@/services/api';
+import { credentialApi } from '@/api';
 import { useConfirm } from '@/components/ui/confirm-dialog';
 import { toast } from 'sonner';
 

frontend/src/components/system/CsvImportDialog.tsx

@@ -17,7 +17,7 @@ import {
   DialogTitle,
 } from '@/components/ui/dialog';
 import { Upload, Download, CheckCircle, XCircle } from 'lucide-react';
-import { userApi } from '@/services/api';
+import { userApi } from '@/api';
 
 interface CsvImportDialogProps {
   importDialogOpen: 'csv' | 'ldap' | null;

frontend/src/components/system/ReplayDialog.tsx

@@ -10,7 +10,7 @@ import {
   DialogTitle,
 } from '@/components/ui/dialog';
 import { Loader2 } from 'lucide-react';
-import { terminalSessionApi } from '@/services/api';
+import { terminalSessionApi } from '@/api';
 
 interface ReplayDialogProps {
   open: boolean;

frontend/src/components/system/SystemLogsTab.tsx

@@ -12,7 +12,7 @@ import {
   TableHeader,
   TableRow,
 } from '@/components/ui/table';
-import { auditApi } from '@/services/api';
+import { auditApi } from '@/api';
 import type { OperationLog } from '@/types';
 
 interface SystemLogsTabProps {

frontend/src/components/system/SystemManager.tsx

@@ -4,7 +4,7 @@ import { useConfirm } from '@/components/ui/confirm-dialog';
 import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
 import { Badge } from '@/components/ui/badge';
 import { CheckCircle, XCircle, Users, Shield, Settings } from 'lucide-react';
-import { userApi } from '@/services/api';
+import { userApi } from '@/api';
 import type { Role } from '@/types';
 import { SystemUserTab } from './SystemUserTab';
 import { SystemRolesTab } from './SystemRolesTab';

frontend/src/components/system/SystemRolesTab.tsx

@@ -7,7 +7,7 @@ import {
   Dialog, DialogContent, DialogDescription, DialogFooter, DialogHeader, DialogTitle,
 } from '@/components/ui/dialog';
 import { Plus, Shield, ShieldCheck, Edit, Eye, Trash2, Lock, Star } from 'lucide-react';
-import { userApi } from '@/services/api';
+import { userApi } from '@/api';
 import { useConfirm } from '@/components/ui/confirm-dialog';
 import type { Role } from '@/types';
 import { RoleFormDialog, type RoleFormData, type PermissionOption } from './RoleFormDialog';

frontend/src/components/system/UserFormDialog.tsx

@@ -17,7 +17,7 @@ import {
   SelectValue,
 } from '@/components/ui/select';
 import { User } from 'lucide-react';
-import { userApi } from '@/services/api';
+import { userApi } from '@/api';
 
 export interface UserFormData {
   username: string;

frontend/src/components/system/useLdapManagement.ts

@@ -1,7 +1,7 @@
 import { useState } from 'react';
 import { toast } from 'sonner';
 import { useConfirm } from '@/components/ui/confirm-dialog';
-import { ldapApi } from '@/services/api';
+import { ldapApi } from '@/api';
 import type { LdapFormData } from './SystemSettingsTab';
 
 /**