Initial commit: Shopify storefront Next.js template

Next.js 16 + React 19 storefront template with Shopify Storefront API
integration, Tailwind v4, and shadcn/ui components.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0111qSr3KopyGRsJ6LznR1xZ

components/ui/sonner.tsx

@@ -0,0 +1,23 @@
+import React from 'react';
+import { toast } from 'sonner';
+
+import Button from '@/components/ui/button';
+
+export function SonnerDemo() {
+  return (
+    <Button
+      variant="outline"
+      onClick={() =>
+        toast('Event has been created', {
+          description: 'Sunday, December 03, 2023 at 9:00 AM',
+          action: {
+            label: 'Undo',
+            onClick: () => console.log('Undo'),
+          },
+        })
+      }
+    >
+      Show Toast
+    </Button>
+  );
+}