feat(web): 移动端适配——顶栏防换行 + 抽屉式侧边栏

- TopBar: 标题区 min-w-0+truncate 防换行；移动端(sm 下)隐藏心情/WS文字tag、管理/主题按钮shrink-0；新增汉堡按钮(md:hidden)
- Nav: 抽共享 NavContent；桌面 Sidebar(dd:flex) 保持；移动端新增 MobileNav 抽屉(遮罩+弹簧滑入 md:hidden)
- App: 加 menuOpen state，渲染 MobileNav + TopBar 传 onMenu
- Icon: 新增 menu 图标；index.css: 加 mu-drawer-in 滑入动画
- npm run build 绿(77模块)；后端未动

frontend/web/src/components/Icon.tsx

@@ -46,7 +46,8 @@ export type IconName =
   | "arrow"          // → direction (arrow_forward_rounded)
   | "terminal"       // 🖥 code (terminal_rounded)
   | "image"          // 🖼 attachment/vision (image_rounded)
-  | "phone"          // 📞 voice call / hang up (call_rounded);
+  | "phone"          // 📞 voice call / hang up (call_rounded)
+  | "menu"           // ☰ drawer/open nav (menu_rounded);
 
 const ICON_PATHS: Record<IconName, string> = {
   chart:
@@ -125,6 +126,8 @@ const ICON_PATHS: Record<IconName, string> = {
     "M21 19V5c0-1.1-.9-2-2-2H5c-1.1 0-2 .9-2 2v14c0 1.1.9 2 2 2h14c1.1 0 2-.9 2-2ZM8.5 13.5l2.5 3.01L14.5 12l4.5 6H5l3.5-4.5Z",
   phone:
     "M6.6 10.8a15.1 15.1 0 0 0 6.6 6.6l2.2-2.2c.3-.3.7-.4 1-.2 1.1.4 2.3.6 3.6.6.6 0 1 .4 1 1V20c0 .6-.4 1-1 1C10.6 21 3 13.4 3 4c0-.6.4-1 1-1h3.5c.6 0 1 .4 1 1 0 1.3.2 2.5.6 3.6.1.3 0 .7-.2 1l-2.3 2.2Z",
+  menu:
+    "M4 6h16v2H4V6Zm0 5h16v2H4v-2Zm0 5h16v2H4v-2Z",
 };
 
 export interface IconProps {