Its provisioner runs DDL by shelling out to psql, which the runtime base has no reason to hold. Every create failed with ENOENT and retried for ever.
Both modules keep their tools in an entrypoint of their own, so an image that named only the consumer would serve none of them.
Its provisioner container named an image nobody could produce — a zero digest placeholder. It names an artifact instead, and the module says how to build it, so the mesh can make the database provider the catalogue needs.