Root cause: PR #330 SF-B3 introduced pydantic EmailStr import in
backend/app/api/v1/pilot.py at module level. EmailStr requires the
email-validator package which is not in pyproject deps, so backend import
crashed:
pydantic.errors.PydanticImportError: `email-validator` is not installed
Result: backend container started but uvicorn import failed → /health
endpoint never bound → docker-compose marked container unhealthy → deploy
exited 1.
Fix: drop EmailStr, use plain `str | None` with a minimal regex pattern.
Strict email validation can run on the frontend or CRM side.
31e686e4d3