fix(s3compatsigv4): ストレージ側エラーの異常系ハンドリングを全面改善(クォータ超過の明示化とコミット成否不明時の案内) - #98

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4, actions/upload-artifact@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/