Edit a panorama and return the updated panorama

Fetches the panorama behind the source (a request_id / world_id you created, or a panorama_id from a previous edit), applies the prompt + optional reference images, and returns the new panorama. Iterate by passing the returned panorama_id back in as the source; create a world from the final panorama via POST /v1/worlds with input { type: "panorama_id" }.