移除页面卸载时的清理逻辑，简化代码

src/pages/U1/u1.tsx

@@ -93,15 +93,6 @@ const U1: React.FC = () => {
     };
   }, [reading, navigate]);
 
-  useEffect(() => {
-    return () => {
-      // 页面卸载时清理
-      if (timerRef.current) clearTimeout(timerRef.current);
-      timerRef.current = null;
-      if (reading) window.electronAPI.stopIdCardListen().catch(() => {});
-    };
-  }, [reading]);
-
   return (
     <div className="u1-root">
       <span className="u1-title">