feat(extension): 同步文档标题动态化功能

- 与 web 包保持一致，实现扩展popup的标题国际化
- 自动设置 HTML lang 属性

Author: linshenkx

packages/extension/src/main.ts

@@ -1,5 +1,5 @@
-import { createApp } from 'vue'
-import { installI18nOnly } from '@prompt-optimizer/ui'
+import { createApp, watch } from 'vue'
+import { installI18nOnly, i18n } from '@prompt-optimizer/ui'
 import App from './App.vue'
 
 import './style.css'
@@ -8,4 +8,18 @@ import '@prompt-optimizer/ui/dist/style.css'
 const app = createApp(App)
 // 只安装i18n插件，语言初始化将在App.vue中服务准备好后进行
 installI18nOnly(app)
+
+// 同步文档标题和语言属性
+if (typeof document !== 'undefined') {
+  const syncDocumentTitle = () => {
+    document.title = i18n.global.t('common.appName')
+    const currentLocale = String(i18n.global.locale.value || '')
+    const htmlLang = currentLocale.startsWith('zh') ? 'zh' : 'en'
+    document.documentElement.setAttribute('lang', htmlLang)
+  }
+
+  syncDocumentTitle()
+  watch(i18n.global.locale, syncDocumentTitle)
+}
+
 app.mount('#app')