Show statistics on home page

Statistical information can be shown on the homepage (screen before searching), such as total uploaded papers, etc.

[Travel Buddy](/metakgp/travel-buddy) shows similar statistics on its home page:

<img width="1124" height="601" alt="Image" src="https://github.com/user-attachments/assets/171bf887-5f74-47e3-9d6a-2f9907dda13d" />