refactor: use Nuxt 4 directory structure

app/app.vue

@@ -0,0 +1,25 @@
+<template>
+  <UApp :locale="zh_cn">
+    <NuxtLayout>
+      <NuxtPage />
+    </NuxtLayout>
+  </UApp>
+</template>
+
+<script setup lang="ts">
+  import { zh_cn } from '@nuxt/ui/locale'
+
+  // TODO
+  useHead({
+    title: 'Deep Research Web UI',
+    script: [
+      // Anonymous analytics
+      {
+        defer: true,
+        src: 'https://umami.ataw.top/script.js',
+        'data-website-id': '9f925777-1c4c-440d-94ae-4bfee9e7aa71',
+        'data-tag': useRuntimeConfig().public.version,
+      },
+    ],
+  })
+</script>