fix: lang fix

src/App.tsx

@@ -43,6 +43,10 @@ function App() {
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []); // 仅用于首屏同步 i18n 语言
 
+  useEffect(() => {
+    document.documentElement.lang = language;
+  }, [language]);
+
   useEffect(() => {
     const timer = setTimeout(() => {
       setSplashReadyToFade(true);