Add external link button to product list items

Opens the product's URL in a new tab directly from the dashboard,
without needing to go to the product detail page first.

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

frontend/src/components/ProductCard.tsx

@@ -350,6 +350,19 @@ export default function ProductCard({ product, onDelete, onRefresh }: ProductCar
       </div>
 
       <div className="product-actions">
+        <a
+          href={product.url}
+          target="_blank"
+          rel="noopener noreferrer"
+          className="btn btn-secondary btn-icon"
+          title="Open product page"
+        >
+          <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+            <path d="M18 13v6a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2V8a2 2 0 0 1 2-2h6" />
+            <polyline points="15 3 21 3 21 9" />
+            <line x1="10" y1="14" x2="21" y2="3" />
+          </svg>
+        </a>
         <button
           className={`btn btn-secondary btn-icon ${isRefreshing ? 'refreshing' : ''}`}
           onClick={handleRefresh}