Bug Report: Copilot-CLI doesn't recognize slash commands

<img width="1419" height="379" alt="Image" src="https://github.com/user-attachments/assets/ce8c89d6-9a7c-46ab-942d-49ef54c750ce" />

After comparing to spec-kit, I found we have to use this structure:

https://github.com/runtime-env/runtime-env/pull/534

---

Thanks for this excellent tool 👍🏻.
