feat(web): bootstrap react vite tailwind shadcn stack

apps/web/src/App.tsx

@@ -0,0 +1,27 @@
+import { Button } from "@/components/ui/button";
+
+function App() {
+  return (
+    <div className="min-h-screen bg-[#f6f8f7] text-[#122117]">
+      <header className="border-b border-[#d7e2db] bg-white/90 backdrop-blur">
+        <div className="mx-auto flex h-16 w-full max-w-6xl items-center justify-between px-4">
+          <div className="flex items-center gap-2">
+            <div className="h-8 w-8 rounded-lg bg-[#0a7a5a]" />
+            <span className="text-lg font-semibold tracking-tight">TodoList</span>
+          </div>
+          <Button className="rounded-md bg-[#0a7a5a] text-white hover:bg-[#0a7a5a]/90">登录</Button>
+        </div>
+      </header>
+      <main className="mx-auto w-full max-w-6xl px-4 py-8">
+        <section className="rounded-xl border border-[#d7e2db] bg-white p-6 shadow-sm">
+          <h1 className="text-2xl font-semibold">Web 壳已就绪</h1>
+          <p className="mt-2 text-sm text-[#3a5a4a]">
+            下一步将接入邮箱验证码登录、OAuth 回调和会话恢复。
+          </p>
+        </section>
+      </main>
+    </div>
+  );
+}
+
+export default App;