## Summary
<!-- What changed and why? Keep this short but specific. -->

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## Linked issue
<!-- Use "Fixes #123" when the PR fully resolves an issue. Use "Refs #123" for partial work. -->

## Type of change
- [ ] Bug fix
- [ ] Feature
- [ ] Performance improvement
- [ ] Documentation
- [ ] Tests
- [ ] Refactor
- [ ] CI / packaging

## Area
- [ ] CSV parser / I/O
- [ ] C++ cleaning engine
- [ ] Python API / ArFrame
- [ ] Pipeline / custom steps
- [ ] Data quality / profiling
- [ ] Schema validation
- [ ] pandas interoperability
- [ ] Docs / website
- [ ] Developer tooling

## Testing
<!-- Paste commands you ran and summarize the result. -->
- [ ] `make test`
- [ ] `make lint`
- [ ] Other:

## Screenshots / Media
<!-- If this PR changes the UI, README visuals, or terminal output, add a screenshot or GIF. -->

## Performance Impact
<!-- If this PR affects speed or memory, paste a snippet from `make benchmark` or other tools. -->

## Contributor checklist
- [ ] I read the contributing guide.
- [ ] I kept the PR focused on one issue or one logical change.
- [ ] I added or updated tests for behavior changes.
- [ ] I added or updated docs/examples for public API changes.
- [ ] I checked that generated files, logs, and local build artifacts are not committed.
- [ ] My PR title uses Conventional Commits (`feat:`, `fix:`, `docs:`, `test:`, `refactor:`, `chore:`).

## Maintainer notes
<!-- Optional: risks, migration notes, release notes, or follow-up work. -->
