Implement full dark mode with system preference detection

[Chuks-coderr]

Overview

The app uses only a light theme. Add a dark mode that activates automatically based on prefers-color-scheme and can be toggled manually.

Acceptance Criteria

• Tailwind dark: classes applied throughout all components
• Toggle button in NavHeader persists preference to localStorage
• System preference detected on first load
• All charts and modals respect the selected theme
• No flash of unstyled content on page load

[Primex-hub]

@sleek007 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I will like to work on this project

ℹ️ Repo Maintainers: To accept this application, review their application or assign @sleek007 to this issue.

[peternnadi1999]

@peternnadi1999 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Please can this be assigned to me 🙏🙏🙏

ℹ️ Repo Maintainers: To accept this application, review their application or assign @peternnadi1999 to this issue.

[brendaamareco]

@brendaamareco has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hey, I'd like to take this one. I've already implemented full dark mode with Tailwind in another project so I know exactly what's needed here. Let me know if it's still open!

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

[Fatimasanusi]

@Fatimasanusi has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this issue

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

[drips-wave]

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

🧑‍💻 @Fatimasanusi: 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.

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[drips-wave]

This issue has been completed by @Fatimasanusi as part of the Stellar Wave Program's 7th Wave 🥳

😎 @Fatimasanusi: You earned 200 Points for completing this issue! After the current Wave ends, you'll be eligible for a percentage of the Wave's reward pool based on the percentage of total points you've earned. Learn more here. You can also Leave a review to share your experience working on this issue.

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