* fix: move History and Download buttons to Settings dialog for cleaner chat interface
* fix: cleanup unused imports/props, add i18n for diagram style
* fix: use npx directly to avoid package-lock.json changes in CI
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Co-authored-by: dayuan.jiang <jdy.toh@gmail.com>
- Use head.sha instead of head_ref for checkout (works for forks)
- For fork PRs: fail with helpful message if formatting needed
- For same-repo PRs: auto-commit and push as before
