Retrieves the OpenAPI definition for a given server from :persistent_term.

Reads and parses an OpenAPI definition file.

Supports multiple file formats (e.g. YAML, JSON) by dispatching to the appropriate parser based on the file extension.

Stores the OpenAPI definition for a given server in :persistent_term.

The provided definition is merged with any previously registered definition for the same server before being stored.

Returns the bundled Swagger UI version used by the OpenAPI integration.

This value corresponds to the static Swagger UI assets shipped with the library and is used for serving the documentation frontend.