fix(ci): add GITHUB_TOKEN to checkout + restore corrupted skill descriptions

- Add token: ${{ secrets.GITHUB_TOKEN }} to actions/checkout@v4 in
  sync-codex-skills.yml so git-auto-commit-action can push back to branch
  (fixes: fatal: could not read Username, exit 128)
- Restore correct description for incident-commander (was: 'Skill from engineering-team')
- Restore correct description for senior-fullstack (was: '>')

.github/workflows/sync-codex-skills.yml

@@ -28,6 +28,7 @@ jobs:
         uses: actions/checkout@v4
         with:
           fetch-depth: 0
+          token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Set up Python
         uses: actions/setup-python@v5