Feat: Add dark mode support

[janvi01]

Is your feature request related to a problem? Please describe.
Add a dark mode toggle on the top beside the GitHub button.

Describe the solution you'd like
Chakra UI supports in built support for mode change button.

for reference - https://chakra-ui.com/docs/styled-system/color-mode

[swetasingh8844]

@janvi01 please assign this issue to me under JWoc'24

[janvi01]

Go ahead @swetasingh8844 feel free to drop in any doubts