Load design elements for admin editing

Pass designJson to DesignCanvas and parse it to restore the design
elements that were submitted for approval, so admins can see and edit
the actual design.

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

src/app/admin/designs/[id]/edit/page.tsx

@@ -110,7 +110,13 @@ export default function EditDesignPage({ params }: { params: { id: string } }) {
         </div>
 
         {/* Full Design Canvas */}
-        <DesignCanvas product={design.product} isAdminEditing={true} />
+        <DesignCanvas
+          product={design.product}
+          isAdminEditing={true}
+          initialDesignJson={design.designJson}
+          initialColor={design.color}
+          initialSize={design.size}
+        />
       </div>
     </div>
   );