Returns a specification to start this module under a supervisor.

See Supervisor.

@spec runtime(keyword()) ::
  {:ok, MingaAgent.ArtifactStores.Runtime.t()}
  | {:error, :invalid_artifact_runtime}

Builds the runtime represented by production defaults plus explicit test name overrides.

@spec start_link(keyword()) :: Supervisor.on_start()

Starts the quota, unique record registry, and lazy store supervisor.