chore: bumped version to 0.2.1

[danielalyoshin]

Summary

Version 0.2.1, a docs only release. It puts the README from #2 on the PyPI page, which only changes with a new release.

• pyproject.toml: version 0.2.0 to 0.2.1.
• CHANGELOG.md: new [0.2.1] entry, dated 2026-09-29. Change the date if the release goes out on another day.

No code changes.

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Checked

• A trial build with Poetry 2.5.1 from a clean copy of this branch. poetry check --lock and twine check pass.
• Compared with the 0.2.0 files on PyPI: the package code and the entry points are identical, the sdist has the same files, and the only change in the metadata is the version and the README text.