Sync published v0.2.1 state - #12

Summary

• record the successful v0.2.1 Trusted Publishing release, public artifact hashes, and release workflow
• mark every post-tag release check complete with independently verified evidence
• advance the development version to 0.2.2.dev0 while keeping the published tag and citation record immutable

Validation

• ruff check .
• ruff format --check .
• mypy src/miniverl
• pytest -q tests/unit/test_release_workflow.py tests/unit/test_pypi_release_verifier.py tests/unit/test_packaging.py (88 passed)
• actionlint 1.7.12
• PyPI and GitHub Release artifacts match byte-for-byte
• clean pip install miniverl==0.2.1, version and doctor checks passed without Torch
• frozen benchmark SHA-256 remains 53fc1d4d5b7adee09618d77ad62d4086ba56b78569832d6fc7c3bcd5c2695bbc