Add a multi-stage Dockerfile for the BFF (.NET 10 sdk -> aspnet runtime,
curl for the healthcheck) and infra/docker-compose.yml running it with a
/health healthcheck. `docker compose up --wait` gates on the container
reporting healthy, which is the compose-up smoke test. Document the path
in the README.
Verified: image builds; `docker compose up -d --build --wait` reports the
container Healthy; host curl http://localhost:8080/health -> 200 Healthy.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
