curl --request POST \
  --url https://api.titletrackr.com/api/v1/file-vault/upload \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: multipart/form-data' \
  --form 'files=<string>' \
  --form folder_id=123 \
  --form files.items='@example-file'

{
  "success": true,
  "message": "<string>",
  "files": [
    {
      "id": 123,
      "filename": "<string>",
      "file_type": "<string>",
      "mime_type": "<string>",
      "page_count": 123,
      "file_size": 123,
      "file_size_human": "<string>",
      "folder_id": 123,
      "is_processing": true,
      "public_url": "<string>",
      "created_at": "2023-11-07T05:31:56Z"
    }
  ],
  "errors": [
    {}
  ]
}