Add Dark Mode Support

[Abd-Standard]

Description
Implement a dark theme that users can switch to without affecting functionality. Theme preference should persist between sessions.

Acceptance Criteria
Dark mode is fully implemented.
Theme preference is saved.
UI remains readable in both themes.

[mikevill20]

@mikevill20 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello maintainer, please assign this issue to me. Thanks

ℹ️ Repo Maintainers: To accept this application, review their application or assign @mikevill20 to this issue.

[Muneerat]

@Muneerat has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hi
Please assign me this task.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Muneerat to this issue.

[itsnotOJ]

@itsnotOJ has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

I would like to work on this issue

ℹ️ Repo Maintainers: To accept this application, review their application or assign @itsnotOJ to this issue.

[drips-wave]

Congratulations, @itsnotOJ! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on July 30, 2026.

🧑‍💻 @itsnotOJ: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

When opening a PR, please link it to this issue to ensure it gets tracked accurately. Points are awarded when this issue is marked as completed by the maintainer.

🤠 Repo maintainers: Please keep an eye on the contributor's progress and review their work before the due date. You can manage this issue, including adjusting its complexity and points, here.

🌊 Happy Wave 🌊