v0.3.1 — GitHub Migration

What's Changed

Fully migrated CI/CD and project infrastructure from GitLab to GitHub.

CI/CD

• GitHub Actions CI — test matrix across Python 3.11, 3.12, 3.13
• Build — hatch-based wheel and sdist via GitHub Actions
• PyPI publishing — OIDC Trusted Publishing (no API tokens)
• TestPyPI — manual workflow dispatch for pre-release testing

Cleanup

• Removed .gitlab-ci.yml
• Removed .readthedocs.yaml
• Updated all project URLs (pyproject.toml, docs/conf.py) to GitHub

Full Changelog: v0.3.0...v0.3.1