panel: Remove unused panel crate (#63742)

# Objective

remove unused crate

## Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content adheres to Zed's UI standards
([UX/UI](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
and
[icon](https://github.com/zed-industries/zed/blob/main/crates/icons/README.md)
guidelines)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

---

Release Notes:

- N/A

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Signed-off-by: Xiaobo Liu <cppcoffee@gmail.com>
Co-authored-by: MrSubidubi <finn@zed.dev>
ab7afbff39Xiaobo Liu committed on 9/4/2026, 10:08:26 AM· committed by GitHubparent80ddc3a
8 files changedLine totals unavailable