微信公众号二维码

Overview

根据微信公众号 ID 生成关注二维码链接，并在用户没有提供 ID 时，用内置引导图帮助用户在微信中找到公众号 ID。

二维码规则：

https://open.weixin.qq.com/qr/code?username={公众号ID}

Workflow

1. If the user provides a公众号 ID, normalize it and generate the QR code URL directly.
2. If the user provides a full QR URL, extract the username value and regenerate the canonical URL.
3. If the user does not provide an ID, show the three guide images from assets/ and ask them to follow the steps to copy the ID.
4. In Agent/Codex chat surfaces, download the QR image to a local file and embed it with an absolute local path. Do not rely on the remote WeChat image URL for Markdown preview.
5. Return the公众号 ID, the canonical URL, and the local image preview.