Follow up future review note: `ensure_explicit_workdir` does not validate that the explicit path's git remote matches `c

[wwind123]

Future follow-up from approved review on PR #49.

Reviewer: Claude

Follow-up:

• ensure_explicit_workdir does not validate that the explicit path's git remote matches config.repo (unlike ensure_temp_checkout which calls _looks_like_repo_remote). For a future PR, adding the same remote check to the explicit-workdir path would give a clearer error if a user accidentally passes the wrong checkout.

This was mentioned in an approved review as future work and did not block merge readiness.