OptionalentitiesOptionalentityDisplay entity count. Defaults to the number of entities. The GLB path
overrides this with its mesh count — the synthetic store carries no entity
rows but still wants to report N renderable meshes to the UI.
OptionalsourceSource bytes for lazy entity extraction. Defaults to empty; with an empty
source getEntity safely returns null (the entity table still answers
type/name/globalId queries from its columns).
Synthetic entity rows; omit (or pass
[]) for an entity-less store.