PyPI package publishing

[MaxwellCalkin]

Setup needed

Configure PyPI trusted publisher for automated releases:

1. Go to https://pypi.org/manage/account/publishing/
2. Add pending publisher:
   • Project: sentinel-ai
   • Owner: MaxwellCalkin
   • Repository: sentinel-ai
   • Workflow: publish.yml
   • Environment: pypi
3. Create a new release to trigger publish

GitHub environments (pypi, testpypi) are already configured.