feat(hackathon): Improve dark mode and UI/UX in Hackathon website (#64)

* feat: update landing page

* feat: Add favicon and SEO (JSON-LD schema, meta tags)

- Add favicon image
- Add JSON-LD schema for Hackathon event
- Add react-helmet-async for managing meta tags

* chore: remove react-helmet-async

* chore: update landing page

* chore: update UI for signup and login

- add back button for better UX

* feat: add image loading state and skeleton UI for team dashboard

* fix: landing navbar not sticky to top, fix onboarding UI

* feat(hackathon): update UI

- Update dashboard, onboarding user, edit profile, and team layout
  to make it more consistent

* fix: optimize placeholder banner image & minor fix dark mode

* feat(hackathon): update landing page dark mode color scheme

* feat(hackathon): update auth page dark mode color scheme

* feat(hackathon): dashboard UI improvement and dark mode adjustment

* feat(hackathon): browse team page

- update dark mode color scheme
- add some border style to give outline and depth
- change emoji to icon

* feat(hackathon): update team page

- update dark mode color scheme for team page: view, team edit,
  and submit project page
- fix bug in chat where messages are displayed double
- make the form field size consistent

* feat(hackathon): update dark mode onboarding and edit profile

---------

Co-authored-by: Maulana Sodiqin <sodiqincahyana1@gmail.com>
Co-authored-by: Muhammad Zakir Ramadhan <61570975+zakirkun@users.noreply.github.com>

apps/hackathon/src/app/teams/layout.tsx

@@ -6,19 +6,19 @@ const TeamsLayout: FC = (): ReactElement => {
   const [sidebarOpen, setSidebarOpen] = useState(false);
 
   return (
-    <div className="flex min-h-screen bg-gray-50 dark:bg-neutral-950">
+    <div className="flex min-h-screen bg-gray-50 dark:bg-gray-950">
       <Sidebar isOpen={sidebarOpen} onClose={() => setSidebarOpen(false)} />
 
       <div className="flex-1 flex flex-col">
         {/* Mobile Header with Hamburger */}
-        <div className="lg:hidden sticky top-0 bg-white dark:bg-neutral-900 border-b dark:border-neutral-700 px-4 py-3 z-10">
+        <div className="lg:hidden sticky top-0 bg-white dark:bg-gray-900 border-b dark:border-gray-700 px-4 py-3 z-10">
           <div className="flex items-center">
             <button
               onClick={() => setSidebarOpen(true)}
-              className="p-2 rounded-lg hover:bg-gray-100 dark:hover:bg-neutral-800 transition-colors"
+              className="p-2 rounded-lg hover:bg-gray-100 dark:hover:bg-gray-800 transition-colors"
             >
               <svg
-                className="w-6 h-6 text-gray-600 dark:text-neutral-400"
+                className="w-6 h-6 text-gray-600 dark:text-gray-400"
                 fill="none"
                 stroke="currentColor"
                 viewBox="0 0 24 24"