alpha

Add PyPI Trusted Publishing workflow (OIDC)

Publishes django-dbs to PyPI on a published GitHub Release using
pypa/gh-action-pypi-publish with OIDC -- no API tokens stored. Pipeline gates
the release behind the test suite and a build/twine-check step. Uses a "pypi"
GitHub environment that the PyPI trusted publisher must reference.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YA3yB4s14FPYZAP7MyJ1K2