Add Dark Mode Toggle for All Pages

[nagarjunpl]

The website currently supports only light mode. Adding a Dark Mode toggle will improve accessibility and enhance the user experience, especially for users browsing at night.

Expected Behavior:

• Add a Dark Mode / Light Mode toggle button in the header.

• Dark Mode should apply to all pages consistently.

• User preference should be remembered (local storage or system preference).

This feature will modernize the UI, improve usability, and provide users with a personalized browsing experience.

[github-actions]

Thank you for raising this issue!

We'll review it as soon as possible. We truly appreciate your contributions! ✨

Meanwhile make sure you've visited the README.md, CONTRIBUTING.md, and CODE_OF_CONDUCT.md before creating a PR for this. Also, please do NOT create a PR until this issue has been assigned to you. 😊

[omroy07]

Assigned