Add structured type query responses

Summary:
Expose a structured response for type query results so clients can consume type names, arguments, callables, and variables without parsing display strings. The response keeps `display` as a compatibility field for existing string-based behavior and includes a top-level `version` field so the schema can evolve without adding another endpoint.

The structured conversion intentionally maps Pyrefly's internal type enum into a smaller client-facing shape: `named`, `callable`, and `variable`. The conversion remains exhaustive over `pyrefly_types::types::Type`, so adding a new Pyrefly type variant requires an explicit mapping at compile time.

`display` is still present for compatibility and debugging. It can be removed or gated in a later schema version once consumers no longer depend on the legacy string representation.

Reviewed By: stroxler

Differential Revision: D105329981

fbshipit-source-id: 4aabc97679fb4cf3d3e8321401d4b9337ac22dee

Author: Anqi Wu