Feat: Add loading spinner for made-to-order page

- Create LoadingSpinner component with spinning circle
- Wrap products grid with Suspense boundary
- Shows spinner while products are loading
- Improves UX for slower connections

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/components/LoadingSpinner.tsx

@@ -0,0 +1,10 @@
+export default function LoadingSpinner() {
+  return (
+    <div className="flex items-center justify-center py-24">
+      <div className="relative h-12 w-12">
+        <div className="absolute inset-0 rounded-full border-4 border-line"></div>
+        <div className="absolute inset-0 animate-spin rounded-full border-4 border-transparent border-t-ink"></div>
+      </div>
+    </div>
+  );
+}