PR review runbook does not include merging

The PR review runbook (Handle a PR review round) ends at: fix → commit → push → reply to all comments → resolve all threads. Do not merge the PR.

Why: The user merges PRs themselves. Attempting gh pr merge after completing review steps is outside the runbook scope and was explicitly corrected (2026-05-30, PR #940).

How to apply: After resolving all review threads, stop and report completion. The user will merge. Merging is only appropriate when running the Work a task through to merged PR runbook (step 8), and only after the PR is approved and CI is green.