feat/ux: use lenis for smooth scrolling, instead of transform to minify css size

Lenis is a library for smooth scrolling. Currently all the scrolling animations are a result of css and js snippets.
- css defines containers,snap,scrollbars.
- js drives auto-focus,recenter,auto-scroll behavior.

Check it out at : [https://www.lenis.dev/](https://www.lenis.dev/)

A couple of things _can_ be fixed here, owing to using lenis, which could be:-
- smoother overview animation
- better overview distribution of windows
- auto-scroll's vertical and horizontal scrolls trigger one after the other, to avoid a race condition triggered by the css-js split. We can change this to a singular movement if possible.
- the footer's rubber band effect also is slow in laptops, but on mobile we have a much faster response. this rubber band effect can be made something into a long scroll/long pull up to stick to the footer (like in voice chat feature for wa groups).

These could be added as sub-issues/separate issues later.

No files or tests are named. Start by reviewing the existing CSS and JavaScript responsible for containers, snapping, scrollbars, auto-focus, recentering, auto-scroll, and the footer effect, then read the Lenis documentation. Define which listed behaviors are in scope; done means the selected scrolling behavior uses Lenis and the relevant overview, auto-scroll, and footer interactions work without the current CSS-JavaScript race condition.

Scritto dal modello di indicizzazione a partire dal testo della issue.