Add 404 page and invitation success screen

- Created NotFound component with proper error messaging and navigation
- Added catch-all route (*) in App.js for undefined routes
- Added success state in AcceptInvitation with user info display
- Auto-redirect after 3 seconds with manual continue button option
- Improved UX with animated success indicator

src/pages/NotFound.js

@@ -0,0 +1,81 @@
+import React from 'react';
+import { useNavigate } from 'react-router-dom';
+import { Button } from '../components/ui/button';
+import { Card } from '../components/ui/card';
+import { Home, ArrowLeft, Search } from 'lucide-react';
+
+const NotFound = () => {
+  const navigate = useNavigate();
+
+  return (
+    <div className="min-h-screen bg-gradient-to-br from-[#F9F8FB] to-white flex items-center justify-center p-4">
+      <Card className="w-full max-w-2xl p-12 bg-white rounded-2xl border border-[#ddd8eb] text-center">
+        {/* 404 Illustration */}
+        <div className="mb-8">
+          <div className="relative">
+            <h1
+              className="text-[180px] font-bold text-transparent bg-clip-text bg-gradient-to-br from-[#ddd8eb] to-[#f9f8fb] leading-none"
+              style={{ fontFamily: "'Inter', sans-serif" }}
+            >
+              404
+            </h1>
+            <div className="absolute inset-0 flex items-center justify-center">
+              <Search className="h-24 w-24 text-[#664fa3] opacity-30" />
+            </div>
+          </div>
+        </div>
+
+        {/* Message */}
+        <h2
+          className="text-3xl font-semibold text-[#422268] mb-4"
+          style={{ fontFamily: "'Inter', sans-serif" }}
+        >
+          Page Not Found
+        </h2>
+        <p
+          className="text-lg text-[#664fa3] mb-8 max-w-md mx-auto"
+          style={{ fontFamily: "'Nunito Sans', sans-serif" }}
+        >
+          Oops! The page you're looking for doesn't exist. It might have been moved or deleted.
+        </p>
+
+        {/* Action Buttons */}
+        <div className="flex flex-col sm:flex-row gap-4 justify-center">
+          <Button
+            onClick={() => navigate(-1)}
+            variant="outline"
+            className="rounded-xl border-2 border-[#664fa3] text-[#664fa3] hover:bg-[#f9f8fb] px-6 py-6"
+          >
+            <ArrowLeft className="h-5 w-5 mr-2" />
+            Go Back
+          </Button>
+          <Button
+            onClick={() => navigate('/')}
+            className="rounded-xl bg-gradient-to-r from-[#664fa3] to-[#422268] hover:from-[#422268] hover:to-[#664fa3] text-white px-6 py-6"
+          >
+            <Home className="h-5 w-5 mr-2" />
+            Back to Home
+          </Button>
+        </div>
+
+        {/* Help Text */}
+        <div className="mt-8 pt-8 border-t border-[#ddd8eb]">
+          <p
+            className="text-sm text-[#664fa3]"
+            style={{ fontFamily: "'Nunito Sans', sans-serif" }}
+          >
+            Need help? Contact us at{' '}
+            <a
+              href="mailto:support@loaftx.org"
+              className="text-[#664fa3] hover:text-[#422268] font-semibold underline"
+            >
+              support@loaftx.org
+            </a>
+          </p>
+        </div>
+      </Card>
+    </div>
+  );
+};
+
+export default NotFound;