ci: automate tagged package releases

[Boussetta]

Closes #7

Summary

Prepare AliasingAtlas for repeatable, versioned public releases through GitHub Actions.

Changes

• Add a tag-triggered release workflow for v*.*.* tags.
• Verify that the Git tag matches project.version in pyproject.toml.
• Build wheel and source distributions.
• Validate distributions with twine check.
• Publish to PyPI using Trusted Publishing and short-lived OIDC credentials.
• Create a GitHub Release with generated release notes and attached distributions.
• Add RELEASING.md with one-time PyPI setup and maintainer checklist.
• Document release status in the README.
• Record release automation in the changelog.

Required Repository Setup

Before the first publish:

• Create or reserve the aliasing-atlas project on PyPI.
• Configure a PyPI Trusted Publisher for:
  • Owner: Boussetta
  • Repository: NyquistNavigator
  • Workflow: release.yml
  • Environment: pypi
• Create the pypi environment in GitHub repository settings.

Until this one-time setup is complete, the workflow will build and validate artifacts but publishing will fail at the publish step.

Validation

• pytest -q: 38 passed
• Ruff: passed
• mypy: no code errors
• Release workflow uses read-only contents access plus OIDC publishing permission.

Commits

This PR intentionally contains focused commits:

• 787e63b ci: automate tagged package releases
• 5408164 docs: add release checklist and PyPI setup
• c13c914 docs: document automated release status
• 1643d23 docs: record release automation

The generated .coverage file is local and not included.