ci: auto-merge changeset version PRs

Only merges PRs created by the changeset action (version bumps),
not contributor PRs. Triggered when changesets.outputs.pullRequestNumber
exists and nothing was published yet.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: deepracticexc

.github/workflows/release.yml

@@ -47,3 +47,9 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           NPM_TOKEN: ${{ secrets.NPM_TOKEN }}
           NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+
+      - name: Auto-merge version PR
+        if: steps.changesets.outputs.published != 'true' && steps.changesets.outputs.pullRequestNumber
+        run: gh pr merge ${{ steps.changesets.outputs.pullRequestNumber }} --squash --auto
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}