ci: automate semantic release workflows

[luisiturrios1]

Summary

• migrate packaging workflow to pyproject.toml and python-semantic-release
• add reusable test workflow plus PR prerelease publishing to PyPI
• replace tag-triggered deployment with release-on-master workflow
• include existing local workflow cleanup and download request updates

Verification

• python -m pytest
• python -m build
• python -m twine check dist/*
• YAML parse check for GitHub workflows

Notes

• PyPI Trusted Publishers must point to prerelease.yml with environment pypi-prerelease and release.yml with environment pypi-release.