Response codes
| 200 | OK (categories added successfully) |
| 400 | Bad JSON format or data |
| 403 | Authentication failed |
| 409 | Bad transaction ID or not in a transaction |
| 500 | Internal server error |
| 200 | OK (categories added successfully) |
| 400 | Bad JSON format or data |
| 403 | Authentication failed |
| 409 | Bad transaction ID or not in a transaction |
| 500 | Internal server error |