fix: use PAT for auto-tag push to trigger release workflow (#28)

GitHub Actions security policy prevents workflows triggered by
GITHUB_TOKEN from triggering other workflows. Use PAT_WORKFLOW_ONLY
secret in checkout so the tag push triggers the release workflow.

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

Author: minsoo-web

.github/workflows/auto-tag.yml

@@ -18,6 +18,7 @@ jobs:
       - uses: actions/checkout@v4
         with:
           fetch-depth: 2
+          token: ${{ secrets.PAT_WORKFLOW_ONLY }}
 
       - name: Check version change
         id: version