## Common Error Responses
All endpoints may return these common error responses:
- **400 Bad Request**: Invalid input data or validation errors
- **401 Unauthorized**: Missing or invalid authentication
- **403 Forbidden**: Insufficient permissions
- **404 Not Found**: Requested resource doesn't exist
- **409 Conflict**: Resource conflict (e.g., duplicate names)
- **422 Unprocessable Entity**: Business rule violations
- **500 Internal Server Error**: Unexpected server errors