ci: Restore lychee link check. Only validate internal links (#32463)

Follow-up to: https://github.com/zed-industries/zed/pull/32460
Follow-up to: https://github.com/zed-industries/zed/pull/30844

Release Notes:

- N/A
9c47c52de5Peter Tripp committed on 6/10/2025, 3:20:07 PM· committed by GitHubparent286b97c
2 files changedLine totals unavailable