Add Dark Mode Toggle Option

[sparshsingh12312]

Problem Statement

There is no option to switch to dark mode in the Appearance section.

Proposed Solution

I want to add an option to switch to dark mode in the appearance section.

Alternatives Considered

We can also add this to the upper right corner of the website next to the new task.

Additional Context

[sparshsingh12312]

May I lead on addressing this issue? @vitaut