DPROD Contracts: dprod:path OWL typing and rdfs:range (5.4)

[jgeluk]

Track: DPROD 1.1 data-contracts post-merge follow-up from PR #156.

Plan item 5.4 of `dprod-contracts/docs/changes-plan.md`. `dprod:path` is currently typed only as `rdf:Property` with no `rdfs:range` — OWL DL reasoners will treat it as untyped, which is unusual for a property that lives in a published ontology.

Decisions needed:

1. `owl:DatatypeProperty` vs `owl:ObjectProperty` vs leave as `rdf:Property` (because the value is either an IRI for the simple-path case or an RDF list for the sequence-path case).
2. Whether to declare an `rdfs:range` (e.g., a union of `rdf:Property` and `rdf:List`).
3. Knock-on impact on item 6.2 (path-traversal sandboxing/grammar) which is downstream of this decision.

Recommend pairing the decision with the path-grammar formalisation in the formal-semantics doc.

cc @tonyseale @matthiasautrata