Create a Completion

curl --request POST \
  --url https://api.optimix.app/v1/completion/ \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "messages": [
    {
      "role": "user",
      "content": "<string>"
    }
  ],
  "prompt_id": "<string>"
}'

{
  "data": {
    "id": "<string>",
    "output": "<string>"
  }
}