[Enhancement] Add Back to Top Floating Action Button

[Aditya948351]

Description

On long pages like the Roadmaps or Wiki, scrolling back to the top of the page manually can be tedious, especially on mobile devices.

Proposed Solution

1. Create a ScrollToTop component that appears fixed at the bottom right of the screen.
2. It should only render/appear when the user has scrolled down at least 300px.
3. When clicked, it should trigger window.scrollTo({ top: 0, behavior: "smooth" }).

Expected Outcome

Better user experience and navigation efficiency on long content pages.

[Tannuu18]

heyy @Aditya948351 i would like to work on this issue. Please assign me this issue.