[Frontend] Add 404 Catch-All Route with Styled Not-Found Page

[devJaja]

🎯 Objective

Add a catch-all route and a styled 404 page so that users navigating to undefined URLs receive meaningful feedback instead of a blank content area inside the AppShell.

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📁 Files to Create

Action	File Path	Description
Create	frontend/src/pages/NotFoundPage.tsx	404 page component with message and navigation link

📁 Files to Modify

Action	File Path	Description
Modify	frontend/src/App.tsx	Add <Route path="*" element={<NotFoundPage />} /> as the last route

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🎨 Design Spec

The NotFoundPage should:

• Display "404 — Page Not Found" as the primary heading
• Include a brief description: "The page you are looking for does not exist or has been moved."
• Provide a "Go to Dashboard" button (links to /dashboard) and a "Go Home" button (links to /)
• Use the project's dark theme CSS variables for consistent styling
• Be wrapped in the AppShell layout for authenticated routes

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📁 Reference Files

File Path	Purpose
frontend/src/components/common/ErrorBoundary.tsx	Reference for error state UI patterns
frontend/src/styles/global.css	CSS variable definitions for theming
frontend/src/pages/LandingPage.tsx	Reference for landing-style CTAs

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✅ Acceptance Criteria

• Create frontend/src/pages/NotFoundPage.tsx
• Add wildcard <Route path="*"> in frontend/src/App.tsx
• Page renders inside AppShell for unknown paths under /*
• Page renders outside AppShell for root-level unknown paths
• "Go to Dashboard" button navigates to /dashboard
• "Go Home" button navigates to /
• Visual design matches the existing dark theme
• Verify navigation works on both desktop and mobile

[fadeelah2007]

Hi Maintainer,
I'd love to implement this 404 catch-all route and styled page. I can quickly set up a responsive, dark-themed 404 page that aligns with the existing design specs and integrates smoothly with React Router and the AppShell layout

[grantfox-oss]

🦊 GrantFox — @fadeelah2007 has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #144)
2. Your PR will be reviewed by the Epta-Node maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign | FWC26 campaign!

@fadeelah2007's PR #206 was approved and merged by @devJaja.

🏆 @fadeelah2007: You earned 35 FoxPoints for this contribution! Your current tier: Explorer (121 total points). Track your full progress on GrantFox.

👏 Great work, @fadeelah2007! Keep contributing to Epta-Node.