curl --request POST \
 --url https://api.caret.so/v1/folders \
 --header 'Authorization: Bearer <your_api_key>' \
 --header 'Content-Type: application/json' \
 --data '{
"name": "Project Alpha",
"ownerUserId": "usr_123456789",
"icon": "📁",
"color": "#4A90E2",
"isPrivate": false
}'

{
  "folder": {
    "id": "fld_123456789",
    "name": "Project Alpha",
    "icon": "📁",
    "parentFolderId": null,
    "createdAt": "2024-01-28T12:00:00Z"
  }
}

{
  "error": {
    "code": "bad_request",
    "message": "Name is required"
  }
}

{
  "error": {
    "code": "unauthorized",
    "message": "Invalid or missing API key"
  }
}

{
  "error": {
    "code": "internal_server_error",
    "message": "Failed to create folder"
  }
}