curl --request POST \
  --url https://api.example.com/api/playground/prepare \
  --header 'Authorization: Bearer <token>'

{
  "session": {
    "id": "<string>",
    "name": "<string>",
    "source": "<string>",
    "status": "<string>",
    "progress": 123,
    "created_at": "<string>",
    "updated_at": "<string>",
    "source_ref": "<string>",
    "row_count": 123,
    "column_count": 123,
    "columns": [],
    "file_size_bytes": 123,
    "file_names": [
      "<string>"
    ],
    "error_message": "<string>",
    "cancel_requested": false
  },
  "ready": true,
  "launched_task": false
}