🎨 feat: implement theme toggle functionality and update styles

[iShelar]

- Add CSS variables for light and dark themes in style.css
- Create theme-toggle.js to manage theme switching and local storage
- Update base.html to include theme initialization script
- Enhance header.html with a theme toggle button for user interaction
- Refactor existing styles to utilize CSS variables for consistency

[iShelar]

Hello. I’m excited about this small improvement to the site’s theme and styles. Whenever you have time, I’d really appreciate your review and any suggestions you have.

@ArcaneIRE @matrixise

[ArcaneIRE]

Hey! The example image looks great! Thanks for your time and effort

Sorry to keep you waiting, unfortunately I've been ill since last Friday. I'll try to take the chance to review it this weekend.

I'm not sure about third party UI components, I'll also take a look at that if @matrixise doesn't get back to you by then

[ArcaneIRE]

Using variables is a nice refactor even outside of outside of the new theme!

[ArcaneIRE]

Thanks for formatting!

[matrixise]

Hey @iShelar and @ArcaneIRE,

Thank you so much for this fantastic contribution! The dark theme implementation looks amazing, and the refactoring to use CSS variables is a really nice improvement.

@iShelar - I really appreciate the time and effort you put into this feature. The screenshots look great, and it's wonderful to see such quality contributions to the project.

@ArcaneIRE - Thanks for the thorough review and for merging this. Your responsiveness is much appreciated.

It's genuinely exciting to see the project moving forward like this. I'm sincerely sorry for my unavailability lately - but seeing contributions like these makes me really happy. This is exactly the kind of progress we want to see!

Thanks again to both of you. Keep up the great work! 🎉

[iShelar]

Thanks so much, @matrixise really appreciate the kind words and encouragement.

I’ve learned a lot about the project from these two PRs, and I’m looking forward to picking up more issues and contributing again soon.