[Feature] MCP 配置页增加“附加信息”字段

[XiaoGe-LiBai]

Affected area

Desktop UI (agent-gui / React)

Problem statement (what should this solve)

建议在 LiveAgent 的 MCP Server 添加/编辑页面中，增加“附加信息”区域，包含以下字段：
描述：用于说明该 MCP 的功能用途。
文档链接：便于快速访问项目源码或官方文档。

Proposed behavior

比如CC Switch 中这样子。 MCP添加的多了容易忘哪个是干嘛使的了

Estimated change scope

No response

Alternatives considered

No response

Pre-submit checklist

• I searched existing issues and pull requests and found no duplicates.
• This proposal is focused on a single feature or improvement.
• I understand a PR should come after this issue is confirmed by maintainers, otherwise it will be converted to draft.