Add logging to check if designDraft exists in localStorage

Log whether designDraft is found when component mounts to help debug
why old designs persist after submission.

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

src/components/DesignCanvas.tsx

@@ -545,6 +545,7 @@ export default function DesignCanvas({ product, isAdminEditing = false }: { prod
 
     // Load design draft (saved when user tried to checkout without login)
     const designDraft = localStorage.getItem(`designDraft_${product.id}`);
+    console.log(`🔍 Looking for designDraft_${product.id}:`, designDraft ? 'FOUND' : 'NOT FOUND');
     if (designDraft) {
       try {
         const data = JSON.parse(designDraft);