Add dark mode and a toggle for themes

[aadi58002]

This apps uses unocss which by default has support for dark mode. You just need to look through documentation and then try out some combinations of dark color and see which fits.

(P.S. it is too blinding at the moment)

[Puja-Mangale]

Hello Maintainers,

I'm interested in contributing to this issue and would like to take it on. Could you please assign this issue to me, or let me know if there are any specific guidelines or additional information I should be aware of before I begin working on it?

Thank you!

[aadi58002]

Ok, try to read about tailwind and unocss, then use there inbuild features to implement dark mode