[Feature Request] Support reading context files from external repositories

Question

**Bug Description**
when I use claude runned inside repo A, it does not use CLAUDE.md from repo B when I ask it to change files for repo B from repo A. Sometimes it is not convenient to use another Claude Code instance from repo B and easier to ask to change from repo A, especially when the changes are close between repo A and B.

**Environment Info**
- Platform: linux
- Terminal: tmux
- Version: 2.1.32
- Feedback ID: 72511237-036d-498e-9acd-88dfe30cc90a

**Errors**
```json
[]
```