fix: Use proper refname in image optimization workflow

- Change from 'HEAD' to '${{ github.ref_name }}' for proper Git reference
- Fixes 'not a full refname' error
- Ensures push works correctly with feature branches
- Uses GitHub Actions built-in ref_name variable

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: hobbytp

.github/workflows/image-optimization.yml

@@ -88,5 +88,5 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.MY_GITHUB_TOKEN }}
         run: |
           git remote set-url origin https://x-access-token:${GITHUB_TOKEN}@github.com/${{ github.repository }}.git
-          git push origin HEAD
+          git push origin ${{ github.ref_name }}
           echo "推送优化后的图片到仓库"