search: include bare rdf:Property entities (currently invisible to search_entities)

[JohnRDOrazio]

Summary

Follow-up to #117. search_entities() iterates only the three OWL property subkinds (OWL.ObjectProperty, OWL.DatatypeProperty, OWL.AnnotationProperty). Properties typed as bare rdf:Property — common in pre-OWL ontologies, RDFS-only vocabularies, and loosely-typed legacy data — are silently excluded from search results.

Current code

ontokit/services/ontology.py (after #117):

type_mapping: dict[str, list[tuple[URIRef, str, str | None]]] = {
    "class": [(OWL.Class, "class", None)],
    "property": [
        (OWL.ObjectProperty, "property", "object"),
        (OWL.DatatypeProperty, "property", "data"),
        (OWL.AnnotationProperty, "property", "annotation"),
    ],
    "individual": [(OWL.NamedIndividual, "individual", None)],
}

A property declared as :hasFoo rdf:type rdf:Property (no OWL subtype) is invisible to the entity search endpoint and won't show up in any frontend autocomplete, picker, or tree.

Why it matters

• Pre-OWL ontologies (RDF/RDFS-only) declare every property as rdf:Property.
• Many SKOS-style or hybrid vocabularies use bare rdf:Property for properties they don't want to commit to a specific OWL kind.
• Some imported third-party vocabularies are loosely typed.

Proposed fix

Add (RDF.Property, "property", None) to the property mapping, then dedupe results by IRI so a property typed as both owl:ObjectProperty AND rdf:Property (belt-and-suspenders, not uncommon) isn't emitted twice. The OWL-subkind result wins; the bare rdf:Property result is dropped.

property_kind=None on the bare-rdf:Property results is already the shape the schema's defensive fallback was built for — see #117.

Sketch

type_mapping["property"].append((RDF.Property, "property", None))

# After the loop, dedupe: keep the entry with non-None property_kind
# when an IRI appears multiple times.
seen: dict[str, EntitySearchResult] = {}
for r in results:
    existing = seen.get(r.iri)
    if existing is None or (existing.property_kind is None and r.property_kind is not None):
        seen[r.iri] = r
results = list(seen.values())

Acceptance

• A property declared as :hasFoo rdf:type rdf:Property (no OWL subtype) appears in search_entities results
• The result's property_kind is None
• A property typed as both owl:ObjectProperty AND rdf:Property is emitted exactly once with property_kind="object" (no duplicate with None)
• Existing tests for OWL subkinds still pass unchanged
• New tests cover both the bare-rdf:Property case and the dedupe case

Out of scope

• Other RDF property characteristics (owl:FunctionalProperty, TransitiveProperty, etc.) — those are modifiers, not kinds; they decorate an existing OWL subtype rather than replace it
• owl:OntologyProperty (mostly built-in vocabulary, rarely user-defined)
• owl:DeprecatedProperty (a flag, not a kind — already surfaced via the deprecated field on EntitySearchResult)

Origin

Surfaced during review of #117 / PR #120 — the defensive property_kind=None fallback was added there but doesn't actually fire today because the iteration is keyed on the three OWL subkinds. This issue closes that gap.