[FE-37] Implement dark mode toggle with persistence

[mftee]

Overview

Implement a dark mode toggle that switches the UI between light and dark themes and persists the preference across sessions inside frontend/cmmty/.

Acceptance Criteria

• Create frontend/cmmty/components/ThemeToggle/ with toggle component and useTheme hook
• Toggle between light and dark Tailwind classes on the html element
• Persist selection in localStorage
• Default to the OS preference (prefers-color-scheme) on first visit
• Animate the toggle icon transition
• Write unit tests for theme switching and persistence

Contribution Folder

All files must be placed inside frontend/cmmty/. Do not modify any file outside this folder.

How to Contribute

Comment on this issue to express interest, fork the repo, build inside frontend/cmmty/ only, and open a PR targeting main.

[Henrichy]

@Henrichy has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

I’d like to implement the dark mode toggle with persistence for the cmmty frontend. I will create a dedicated ThemeToggle component and a reusable useTheme hook to manage theme state across the application. The solution will toggle Tailwind’s dark/light classes on the html element, ensuring consistent theming across all pages. I will also persist the user’s preference in localStorage so it remains after reloads, while defaulting to the system prefers-color-scheme on first visit. To improve UX, I will add a smooth icon transition animation during toggling. Additionally, I will write unit tests to validate theme switching logic and persistence behavior. All work will remain strictly within frontend/cmmty/, following the contribution rules.

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

[ayshadogo]

@ayshadogo has applied to work on this issue as part of the Stellar Wave Program's 4th wave.

Hello,
I would like to contribute to this issue and resolve it.
Thank you.

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

[drips-wave]

Congratulations, @ayshadogo! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on April 29, 2026.

🧑‍💻 @ayshadogo: 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 @ayshadogo as part of the Stellar Wave Program's 4th Wave 🥳

😎 @ayshadogo: 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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