feat(ui): Enhance homepage responsiveness and layout

This commit introduces several UI improvements to enhance the responsive design and visual appeal of the homepage and main layout.

Key changes include:
- Adjusted the main header to be centered on mobile devices for better alignment.
- Refined the hero section on the homepage with responsive text sizes and improved spacing.
- Modified the "dynamic island" image container to adapt its size and position across different screen sizes.
- Improved typography and layout in the "democratizing tenders" section for better readability.
- Reorganized the contact page into a Next.js route group for better project structure.

app/not-found.tsx

@@ -0,0 +1,7 @@
+interface IProps {}
+
+const NotFound = ({}: IProps) => {
+  return <div>Not found</div>;
+};
+
+export default NotFound;