Add customer approval status messages and admin delete option

Customer-facing changes:
- Show approval status message when design is submitted
- Display pending approval notification with email confirmation
- Show approved confirmation when design is ready
- Show rejection message for designs needing changes

Admin-facing changes:
- Add delete button to design approval detail page
- Confirmation dialog before deletion
- Proper cleanup of design and associated messages
- Redirect to designs list after deletion

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

src/components/DesignCanvas.tsx

@@ -1125,6 +1125,22 @@ export default function DesignCanvas({ product }: { product: ProductDTO }) {
           </div>
         </div>
 
+        {approvalStatus === 'PENDING' && (
+          <p className="text-sm text-orange-600 bg-orange-50 border border-orange-200 px-4 py-3 rounded">
+            ⏳ Your design is pending admin approval. You'll receive an email when it's ready to add to your bag.
+          </p>
+        )}
+        {approvalStatus === 'APPROVED' && (
+          <p className="text-sm text-pine bg-green-50 border border-green-200 px-4 py-3 rounded">
+            ✓ Your design has been approved! You can now add it to your bag.
+          </p>
+        )}
+        {approvalStatus === 'REJECTED' && (
+          <p className="text-sm text-splash-pink bg-red-50 border border-splash-pink/30 px-4 py-3 rounded">
+            Your design needs changes. Check your messages for feedback.
+          </p>
+        )}
+
         <div className="grid grid-cols-2 gap-4">
           <div>
             <p className="tag-label mb-2">Color</p>