Add Custom 404 Not Found Page #129

Description

Currently, when users visit a non-existent route (e.g. /xyz), the website shows a blank or default error page.
To improve user experience, a custom 404 Not Found page should be added that matches the overall QuickFactChecker theme.

Proposed Solution

• Create a new 404 page or component.
• Display a friendly message like:
  “Oops! The page you’re looking for doesn’t exist.”
• Add a “Go Home” button that redirects to /.
• Include relevant visuals (like an illustration or icon).
• Ensure the page is responsive and matches the project’s theme colors.

I'd like to work on this issue ,,Assign it to me @Deepika14145