`FTS()` rejects JSON columns because validation only considers their
`LargeBinary` storage type. Validate the complete Arrow field in
embedded and remote creation so `lance.json` columns reach Lance's
existing JSON-aware inverted index, while ordinary binary fields remain
rejected.
JSON searches use path-qualified triples such as `meta.tag,str,nature`;
the API documentation describes this syntax and its field-scoping
behavior. Remote creation preserves the supplied FTS configuration.
Two integration limits remain: malformed triples can still panic in the
pinned Lance dependency (tracked by lance-format/lance#8812 and the
pending fix in lance-format/lance#8813), and the opt-in server test has
not run against a real deployment because no remote database is
configured. That test covers index completion, statistics, search
results, and index use; HTTP mock coverage only verifies the client
request.
Refs #3891.