### Error Codes
Unless otherwise specified, endpoints follow these standard error responses:
| Status Code | Description |
|  --- | --- |
| `400` | Bad Request (validation errors) |
| `401` | Unauthorized |
| `403` | Forbidden |
| `404` | Not Found |
| `409` | Conflict (business rule failed) |
| `422` | Unprocessable Entity (process validation) |
| `429` | Too Many Requests |
| `500` | Internal Server Error |