📄️Create a chat completion
OpenAI Chat Completions, on any model in the catalog. Send `model` (an alias) and `messages`; set `stream: true` for `text/event-stream` chunks terminated by `data: [DONE]`. Parameters the target model cannot take are dropped and named in `X-MindsHub-Dropped-Params`, and parts of the request the target cannot carry in `X-MindsHub-Dropped-Content` (a stream whose 200 went out early carries neither); `response_format` is the one thing refused with a 400 instead. The response's `model` names the model that served (`mindshub_air` and `mindshub_blaze` return their own alias), and it can be sent back as-is.