Umbrella task to track inconsistencies between SonataFlow runtime behavior and the generated OpenAPI/clients. Scope includes:

(1) POST should return 201 Created (spec shows 200)
(2) when no outputSchema is defined, default POST response to JsonNodeModelOutput instead of null
(3) resolve schema/title-related issues that produce recursive/self-typed models (e.g., workflowdata typed as the enclosing class)

Example for reference: https://github.com/ricardozanini/sonataflow-subflows