Prepare PyPI publishing for springclean

[marioribeiro]

Summary

Prepares Spring Clean to be published as the springclean Python package on PyPI.

Changes

• Rename the distribution package from springclean-audit to springclean.
• Add PyPI-facing project URLs and modern MIT license metadata to pyproject.toml.
• Add build and twine to the development extras.
• Add a GitHub Actions publish workflow using PyPI Trusted Publishing:
  • manual workflow runs publish to TestPyPI
  • v* tag pushes publish to PyPI
• Update the README install flow for PyPI users.
• Document the Trusted Publishing setup values and release process.

Manual follow-up after merge

• Create pending trusted publishers for springclean on TestPyPI and PyPI.
• Create GitHub environments named testpypi and pypi.
• Require manual approval on the pypi environment.
• Run the Publish workflow manually to verify TestPyPI.
• Push v0.1.0 when ready to publish the real PyPI release.

Verification

• ruff check .
• ruff format --check .
• coverage run -m pytest && coverage report
• python -m build
• python -m twine check dist/*
• installed dist/springclean-0.1.0-py3-none-any.whl in a clean virtual environment and checked springclean --version / springclean --help