Add a new sponsor N-iX to JSON Schema website

## Description
- Add a new bronze sponsor N-iX to JSON Schema website.

## Details
N-iX URL:https://www.n-ix.com/ 
Logo: 

<img width="938" height="625" alt="Image" src="https://github.com/user-attachments/assets/f94ea7cd-3c6c-410b-a010-62bab44084f5" />