An optional convenience struct_resolver resolving Namespace/Name references to .dxns files on disk.

Composing multiple compiled schemas into one registry needs no special mechanism at all — Dextrin.Schema.compile/3's base_registry parameter threads across repeated calls. What genuinely needs a policy decision is automatically resolving a bare Namespace/Name reference to a file path, and this module is one reasonable, swappable answer to that — not a mandated convention baked into Dextrin.Registry/Dextrin.Schema itself. Anyone with a different convention in mind writes their own struct_resolver function directly against put_resolver/2; this module exists only because the convention below is a common, unsurprising default, not because it's the only correct one.

Convention: Namespace/Name resolves to <search_path>/Namespace.dxns, read for the specific entry named Name — a .dxns file is already a map of possibly-many schema names, so "Namespace" names the file, "Name" one schema defined inside it. A bare reference with no / (Name) resolves to <search_path>/Name.dxns, read for the entry also named Name — the same rule, just with the file and the entry sharing one name when there's no namespace to separate them.