feat(frontend): M9 模态 UI（mode 系统+共享 store+WS 客户端 + chat(思维链/工具回显/情绪徽标)/code/Agent 监控/后台思考页 + Miuix 设计 token + PWA）；tsc+vite build 通过

frontend/web/src/App.tsx

@@ -0,0 +1,30 @@
+import { useEffect } from "react";
+import { TopBar } from "./components/TopBar";
+import { Sidebar, BottomNav } from "./components/Nav";
+import { ModeRouter } from "./modes/ModeRouter";
+import { connectWs, disconnectWs } from "./lib/ws";
+import { initTheme } from "./lib/theme";
+import { getAuthToken } from "./lib/api";
+
+export default function App(): React.ReactNode {
+  // Apply the persisted (dark-first) theme and open the realtime channel only
+  // when we hold a token — otherwise the gateway rejects the handshake with 401.
+  useEffect(() => {
+    initTheme();
+    if (getAuthToken()) connectWs();
+    return () => disconnectWs();
+  }, []);
+
+  return (
+    <div className="flex h-full flex-col">
+      <TopBar />
+      <div className="flex min-h-0 flex-1">
+        <Sidebar />
+        <main className="relative flex-1 overflow-y-auto pb-[var(--mu-bottomnav-h)] md:pb-0">
+          <ModeRouter />
+        </main>
+      </div>
+      <BottomNav />
+    </div>
+  );
+}