Add stats in feed header

> It's kind of empty. I would bring the statistics here.
> Total articles. Popular categories.

request from private messages

<img width="1563" alt="Screenshot 2024-04-18 at 15 09 14" src="https://github.com/gravity-ui/blog-constructor/assets/36075690/da824755-349d-44d9-bf85-bfb45add047b">
