DEVX-179: fix: strip [skip ci] tokens and prefer newest commit in squash titles

docs/specs/DEVX-179.md

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+# DEVX-179: auto-merge must never select `[skip ci]` squash titles
+
+## Problem
+
+PR #351 squash-merged as `DEVX-178: chore: update badge URLs to commit
+4422c70b [skip ci]`. `extract_conventional_msg` picked a commit subject
+carrying `[skip ci]` — a master badge commit surfaced in the PR's commit
+list after force-push/amend rewrote branch history. The resulting merge
+commit suppressed the post-merge push run: no release, no publish, no
+wiki sync, no Vikunja close.
+
+PR #352 shows the secondary defect: two `ci:` commits on the branch and
+the older one won the tie, so the squash title described a throwaway
+retrigger commit instead of the real change.
+
+## Approach
+
+REQ-1: Subjects containing `[skip ci]`, `[ci skip]`, or `[skip actions]`
+(case-insensitive) are ineligible merge titles. They are excluded before
+priority scoring, so a badge/chore/`[skip ci]` commit can never suppress
+the post-merge pipeline again.
+
+REQ-2: Equal-priority ties resolve to the newest commit in the returned
+list (Gitea returns PR commits newest-first; iterate in returned order
+and keep the first best candidate).
+
+## Test Plan
+
+- `test_auto_merge.py`: commits `[ci retrigger, badge-chore-skipci]` →
+  the `ci` subject wins; commits `[older-ci, newer-ci]` → newest wins;
+  all commits `[skip ci]` → falls back to newest non-skipped subject.
+- `make pytest-cov` (100% gate), `make lint-all`.
+
+## Deploy Plan
+
+Merge as `fix:` → post-merge cuts a release that also ships DEVX-178's
+PLAYBOOK_ROLE_MAP entry.
+
+## Rollback Plan
+
+Revert the squash commit; extract behavior returns to the previous
+(unhardened) selection.
+
+## Acceptance Criteria
+
+- [x] REQ-1: `[skip ci]`/`[ci skip]`/`[skip actions]` subjects are never
+  selected.
+- [x] REQ-2: Equal-priority ties pick the newest commit.
+- [x] Unit tests cover both; 100% coverage maintained.