Review of the registry work found it node-scoped: a second `distribution` on another
machine resolved cleanly there, and only afterwards did the mesh notice `artifact-store`
offered by two nodes, with every consumer elsewhere refusing to choose. Worse, a node-scoped
requirement with one candidate installs that candidate, so anything that wanted the store
beside it would have raised a fresh, empty store on the wrong machine first.
There is one store in a mesh, which was already the effective rule; the claim now says it
where a second one is assigned, by name, instead of leaving consumers to discover it.