Add PracHub as an interview practice resource

Hi, I'd like to suggest adding PracHub to this resource list.

Resource: https://prachub.com

Suggested section: Curated Problems or a new Interview Practice Tools section.

Suggested entry:

- [PracHub](https://prachub.com) - Practice 8,500+ real tech-interview questions from 400+ companies, including coding, SQL, ML, and system design, with an in-browser editor and AI-assisted hints.

Why it fits: this repo collects resources for DSA and coding interview preparation. PracHub is a freemium interview-practice resource with company-specific coding questions plus related SQL, ML, and system-design practice.