fix: respect base URL during QR login

[fishioon]

No description provided.

[NewFuture]

Thanks for working on the QR-login base URL lifecycle. This gap is still present in the current community release, and we would prefer an author-led port rather than copying the patch out of its original context.

If you are interested, we would be glad to review a focused PR against:

https://github.com/NewFuture/openclaw-weixin

A focused port containing only the QR/base-URL behavior would be easiest to review. Please cover initial QR creation, refresh, polling, IDC redirect handling, account-specific persisted URLs, and legacy credential compatibility. This is also the more complete direction compared with the overlapping #190 proposal.

Contribution guide:
https://github.com/NewFuture/openclaw-weixin/blob/main/CONTRIBUTING.md

For transparency, NewFuture/openclaw-weixin is a community-maintained distribution, not the official Tencent/Weixin release.

中文补充：如果你愿意，欢迎基于社区仓库当前 main 分支提交一个聚焦于二维码登录 Base URL 的 PR；我们会保留原作者署名并按当前账号兼容性要求协助 review。