[Feature] 希望支持引用/访问外部项目目录

[ViCrack]

Affected area

Desktop UI (agent-gui / React)

Problem statement (what should this solve)

写代码时参考外部仓库很不方便：

开发中经常需要对照外部仓库的代码，但又不想把那个仓库设成当前项目。

拖入聊天只能选普通文件，文件夹会被拒绝，没法一次把整个外部仓库拖进来。
Agent 读写工具似乎只能访问当前工作区，外部项目路径读不到（像被权限/沙箱拦住了）。

如图：

Proposed behavior

支持把外部文件夹拖入/添加为可读参考目录；或允许在权限范围内把额外目录加入 Agent 可读路径。

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.