The health router is mounted at prefix="/api" in domaindingo's main.py, so
/health 404s. Checking it would have failed every deploy and rolled back a
perfectly good image.
Also adopts three conventions from the vault's DomainDingo Development note:
recreate a single named service (--no-deps --force-recreate), validate with
compose config --quiet before touching the running container, and write the
rollback record in the documented format and location.