fix: 修复微信扫码登录后页面跳转问题

修改 iframe 显示条件,仅在 WAITING 状态时显示 iframe,
当状态变更为 SCANNED/AUTHORIZED 时立即移除 iframe,
防止微信页面执行父页面跳转操作。

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/components/Auth/WechatRegister.js

@@ -501,7 +501,7 @@ export default function WechatRegister() {
                 bg="gray.50"
                 boxShadow="sm"             // ✅ 添加轻微阴影
             >
-                {wechatStatus !== WECHAT_STATUS.NONE ? (
+                {wechatStatus === WECHAT_STATUS.WAITING ? (
                     /* 已获取二维码：显示iframe */
                     <iframe
                         src={wechatAuthUrl}