[FE-33] Create custom 404 and 500 error pages

[yusuftomilola]

Overview

Create custom Next.js 404 and 500 error pages that match the ManageHub design system. All work goes in frontend/sandbox/.

Acceptance Criteria

• frontend/sandbox/not-found.tsx implements a custom 404 page
• frontend/sandbox/error.tsx implements a custom error boundary page (500)
• 404 page includes: "Page not found" heading, a brief message, and a "Go to Dashboard" button
• 500 page includes: an error message, a "Try again" button (calls reset()), and a "Go home" link
• Both pages are responsive and styled with Tailwind CSS
• Both pages include an appropriate SVG illustration or Heroicon
• Navigating to a non-existent route in the sandbox correctly renders the 404 page

[blegodwin]

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

Hi, I’d like to work on this issue. I have experience with large-scale JS applications and will provide a robust, well-tested PR.

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

[drips-wave]

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

🧑‍💻 @blegodwin: 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 🌊

[drips-wave]

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

😎 @blegodwin: 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.