research-plan-implement v5.0.1

[5.0.1] - 2026-08-31

Fixed

• /prepare-pr's tuicr walkthrough documented a reply endpoint that 404s. Replying to
  a review comment needs the PR number:
  gh api repos/{owner}/{repo}/pulls/<n>/comments/<id>/replies. The shorter
  pulls/comments/<id>/replies form it previously showed does not resolve.