Improvement: Add Content Security Policy headers

[LaGodxy]

Summary

The app lacks a Content Security Policy header, making it vulnerable to XSS attacks.

Acceptance Criteria

• CSP header configured in next.config.ts
• Nonce-based inline script allowlist
• Report-only mode first, then enforce
• CSP violation reporting endpoint

[Yusufolosun]

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

Hi Maintainer, Good day
Please can you entrust the implementation of this issue to me. I am a Full Stack Developer and I can deliver maintainable solution that align with your codebase

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

[drips-wave]

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

🧑‍💻 @Yusufolosun: 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

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🤠 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 🌊

[drips-wave]

This issue has been completed by @Yusufolosun as part of the Stellar Wave Program's 4th Wave 🥳

😎 @Yusufolosun: 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.

🧑‍💻 Repo maintainers: How'd the contributor do? Leave a review to share your experience working with them.