fix(admin): 微信扫码恢复前台不再换码——修复'已扫未确认被换码丢确认'竞态

frontend/web/src/admin/modules/channels/WeixinLogin.tsx

@@ -118,14 +118,15 @@ export function WeixinLogin({
   // Track tab visibility: while hidden, do NOT swap the QR (show "过期" overlay instead);
   // on returning, re-mint a fresh code if we were still waiting.
   useEffect(() => {
+    // Restoring the tab must NOT re-mint a QR: if the user has already scanned
+    // (but not confirmed) the on-screen code, swapping it mid-flow cancels the
+    // in-progress bind and WeChat's confirm never lands. Re-minting is only done
+    // by the periodic timer or the explicit 刷新二维码 button.
     const onVis = () => {
-      const h = document.hidden;
-      setHidden(h);
-      if (!h && statusRef.current === "waiting") refreshQR();
+      setHidden(document.hidden);
     };
     const onFocus = () => {
       setHidden(false);
-      if (statusRef.current === "waiting") refreshQR();
     };
     document.addEventListener("visibilitychange", onVis);
     window.addEventListener("focus", onFocus);