feat(audit): F1+F2 告警静默规则标记完成 + 审计日志CSV导出实现

F1 告警静默规则 [done]:
- 后端 alert_silence.go: CRUD + Toggle (onetime/daily/weekly 三模式)
- 告警引擎 isSilenced 集成 (alert_engine.go)
- 前端 SilenceRuleTab + SilenceDialog
- 路由 /alerts/silences 已注册

F2 审计日志导出 [done]:
- 重写 ExportAuditLogs: 真正的 CSV 导出 (encoding/csv + UTF-8 BOM)
- 支持 module/action/username/startTime/endTime 筛选
- 导出限制 10000 条防溢出，自动记录审计日志
- JSON 格式向后兼容 (format=json)
- 前端 exportLogs 传递查询参数

同时包含累积的前期工作:
- 目录重构 internal/ -> controller/model/router (v0.55-v0.57)
- 后端分层架构 dto/repository/service/utils
- 审计模块全功能 (终端审计/操作审计/登录日志)
- asciicast v2 录制格式
- SFTP 文件浏览器
- StatStrip 紧凑统计条
- 在线会话自动刷新
- LiveMonitor WebSocket 诊断修复

验证: go build ✅ | npm run build ✅ | Docker 部署 ✅ | 10 回归端点 ✅ | CSV 导出 ✅ | 静默 CRUD ✅

frontend/src/components/layout/Sidebar.tsx

@@ -35,6 +35,9 @@ import {
   Boxes,
   Clock,
   Rocket,
+  ShieldCheck,
+  FileSearch,
+  LogIn,
 } from 'lucide-react';
 
 import { Button } from '@/components/ui/button';
@@ -132,14 +135,26 @@ const menuItems: MenuItem[] = [
       { id: 'ai-predictive', name: '容量预测', icon: BarChart3, path: '/ai-predictive' },
     ],
   },
-  { id: 'approval', name: '资源申请', icon: CheckSquare, path: '/approval' },
+  { id: 'approval', name: '资源申请', icon: CheckSquare,
+    children: [
+      { id: 'approval-resource', name: '资源申请', icon: Server, path: '/approval/resource' },
+      { id: 'approval-app', name: '应用申请', icon: Rocket, path: '/approval/app' },
+      { id: 'approval-permission', name: '权限审批', icon: ShieldCheck, path: '/approval/permission' },
+    ],
+  },
+  {
+    id: 'audit', name: '安全审计', icon: FileSearch,
+    children: [
+      { id: 'audit-terminal', name: '终端审计', icon: Terminal, path: '/audit/terminal' },
+      { id: 'audit-operations', name: '操作审计', icon: FileCode, path: '/audit/operations' },
+      { id: 'audit-login', name: '登录日志', icon: LogIn, path: '/audit/login-logs' },
+    ],
+  },
   {
     id: 'system', name: '系统管理', icon: Settings,
     children: [
       { id: 'users', name: '用户管理', icon: Users, path: '/users' },
       { id: 'roles', name: '角色权限', icon: Shield, path: '/roles' },
-      { id: 'logs-audit', name: '操作审计', icon: FileCode, path: '/logs-audit' },
-      { id: 'terminal-audit', name: '终端审计', icon: Terminal, path: '/terminal-audit' },
       { id: 'credentials', name: '凭证配置', icon: Shield, path: '/credentials' },
       { id: 'settings', name: '系统设置', icon: Settings, path: '/settings' },
     ],