curl --request POST \
  --url https://api.retab.com/v1/evals/classify/extract/{project_id} \
  --header 'Api-Key: <api-key>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'document=<string>' \
  --form 'model=<string>' \
  --form 'metadata=<string>'

{
  "result": {
    "reasoning": "<string>",
    "classification": "<string>"
  },
  "usage": {
    "credits": 123
  }
}