refactor(frontend): P1-P2 架构统一 — utils/hooks/api 模块化

P1:
- utils/storage.ts、theme.ts、validate.ts + index 统一出口
- request/store/useTheme 接入 storage；清零 confirm/alert
- PipelineManager、TerminalAuditTab 拆分子模块（<700行红线）

P2:
- api/monitor、api/deploy 子目录化
- hooks/api 扩展：servers/pipelines/alerts/audit/sessionCommands
- PipelineManager、AuditOperationsTab 接入 TanStack Query

frontend/src/store/index.ts

@@ -1,6 +1,7 @@
 import { create } from 'zustand';
 import { persist } from 'zustand/middleware';
 import type { User } from '@/types';
+import { removeItem, STORAGE_KEYS } from '@/utils/storage';
 
 // 主题状态
 interface ThemeState {
@@ -40,7 +41,10 @@ export const useUserStore = create<UserState>()(
       setToken: (token) => set({ token }),
       setPermissions: (permissions) => set({ permissions }),
       login: (user, token, permissions) => set({ user, token, isAuthenticated: true, permissions: permissions ?? null }),
-      logout: () => { localStorage.removeItem('token'); set({ user: null as User | null, token: null as string | null, isAuthenticated: false, permissions: null }); },
+      logout: () => {
+        removeItem(STORAGE_KEYS.token);
+        set({ user: null as User | null, token: null as string | null, isAuthenticated: false, permissions: null });
+      },
     }),
     {
       name: 'user-storage',