Public Competitions API - next and previous links

When calling the public compeittions api e.g. `https://www.codabench.org/api/competitions/public/?page=2` the next and previous links show other domain name:

<img width="715" height="233" alt="Image" src="https://github.com/user-attachments/assets/b38bac5f-320b-4630-a373-035e434ee492" />