v1.27.0

First PyPI-published version of bragi. Distribution name is bragi-cms
(the bragi name on PyPI is held by The Managarm Project's IDL;
Pillow precedent: distribution name differs from import name). Import
path stays import bragi; pip install bragi-cms==1.27.0 is now
the canonical pip install path.

Added

• .github/workflows/release.yml: publishes bragi-cms to PyPI on
  every GitHub Release via OIDC Trusted Publishers (no API token in
  GitHub secrets). This is the first release to use it.

Changed

• Distribution name changed from bragi to bragi-cms on PyPI (the
  bragi name is held by The Managarm Project's IDL). Import path
  stays import bragi; console scripts bragi, bragi-admin, and
  bragi-delivery are unchanged. Operators write
  pip install bragi-cms==1.27.0.
• Alembic migrations moved from the project root alembic/ directory
  into the bragi Python package (src/bragi/alembic/) so they ship
  inside the wheel and are accessible after pip install bragi-cms.
  The alembic.ini script_location updated to bragi:alembic
  (package-relative, supported since alembic 1.7).
• New CLI commands bragi db upgrade [REVISION] and
  bragi db downgrade REVISION wrap alembic using the bundled
  migration scripts; works from any working directory after a wheel
  install. The alembic CLI with alembic.ini remains supported for
  development workflows.