Fix: Approve & Add to Bag button not working

- Add JSON body to approve API request
- Add Content-Type header
- Add error handling with user-friendly messages
- Log errors to console for debugging

The button now properly sends the approval request and adds
the design to the customer's bag.

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

src/app/designs/[id]/review/page.tsx

@@ -44,7 +44,11 @@ export default function DesignReviewPage({ params }: { params: { id: string } })
     if (!design) return;
     setApproving(true);
     try {
-      const res = await fetch(`/api/designs/${params.id}/approve`, { method: 'POST' });
+      const res = await fetch(`/api/designs/${params.id}/approve`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({}),
+      });
       if (res.ok) {
         const updated = await res.json();
         setDesign(updated);
@@ -70,7 +74,12 @@ export default function DesignReviewPage({ params }: { params: { id: string } })
         });
 
         alert('Design approved! Added to your bag.');
+      } else {
+        alert('Failed to approve design. Please try again.');
       }
+    } catch (error) {
+      console.error('Error approving design:', error);
+      alert('An error occurred. Please try again.');
     } finally {
       setApproving(false);
     }