Implement OpenAPI 3.0 specification using cl-sdk/cl-json

[Copilot]

Bootstraps cl-openapi from a stub package into a full OpenAPI 3.0 document parser backed by cl-sdk/cl-json.

Core implementation

• types.lisp — CLOS classes for all 24 OAS 3.0 objects: openapi-document, info, contact, license, server, server-variable, path-item, operation, parameter, header, request-body, media-type, encoding, response, example, link, tag, schema, discriminator, xml, security-scheme, oauth-flows, oauth-flow, reference
• decode.lisp — json:decode-json specializations for each type; $ref objects decode to reference instances transparently. Top-level entry point: cl-openapi:parse
• package.lisp — exports ~120 symbols covering all types and their accessors

Usage

(let* ((doc (cl-openapi:parse "{\"openapi\":\"3.0.0\",\"info\":{\"title\":\"Pets\",\"version\":\"1.0\"},\"paths\":{\"/pets\":{\"get\":{\"operationId\":\"listPets\",\"responses\":{\"200\":{\"description\":\"OK\"}}}}}}"))
       (op  (cl-openapi:path-item-get (gethash "/pets" (cl-openapi:openapi-paths doc)))))
  (cl-openapi:operation-id op))  ; => "listPets"

$ref pointers decode to reference instances; callers resolve them against components as needed.

Infrastructure

• qlfile — declares cl-sdk/cl-json and cl-sdk/meta-definitions as qlot GitHub dependencies (neither is in the standard Quicklisp dist)
• CI — updated run step to qlot exec ros run -- so qlot-managed packages are on the load path
• Tests — 14 FiveAM tests covering document structure, schemas, $ref, composition (allOf/anyOf/oneOf), components, and responses