curl --request POST \
  --url http://localhost:8080/v1/files \
  --header 'Content-Type: multipart/form-data' \
  --form file='@example-file' \
  --form purpose=batch \
  --form 'provider=<string>'

{
  "id": "<string>",
  "object": "<string>",
  "bytes": 123,
  "created_at": 123,
  "filename": "<string>",
  "purpose": "<string>",
  "status": "uploaded",
  "storage_backend": "api",
  "extra_fields": "<unknown>"
}