Add dark mode toggle

[joelpeace48-cell]

Add a theme toggle (light/dark) and persist preference (localStorage). Apply CSS variables or class for theme.

[bytebinders]

@bytebinders has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I would like to take this job, I can do it.

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[Babigdk]

@Babigdk has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

I can implement this issue

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[D240021]

@D240021 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hi! 👋

I’d like to contribute to this issue.

I’m a full-stack developer currently getting started in Web3, and I think this project is a great opportunity to learn while contributing to something meaningful in the ecosystem. I have experience working with backend services, REST APIs, and web applications, and I’m motivated to collaborate and add value wherever possible.

Please let me know if I can take this issue. I’d be happy to work on it 🚀

ℹ️ Repo Maintainers: To accept this application, review their application or assign @D240021 to this issue.