v2.13.1

Fixed

• Two v2.13.0 release-doc gaps found by that release’s own AI-review response loop (#925): the #approval-ceiling configuration reference said GitLab and Bitbucket “never post a real approval state”, stale as of issue #918 (Bitbucket now makes real approve/request-changes calls, capped by approval-ceiling the same as GitHub/GitLab), also missing a dedicated AI_BITBUCKET_REVIEW_STATE row. Issue #918’s Bitbucket default-on real-approval behavior is now also flagged as a Behavior change with upgrade guidance, since it can affect branch-restriction rules with no opt-in step. Docs-only, no code changed.

See CHANGELOG.md for full technical detail.