fix: change product cards layout from vertical to horizontal

Changed product cards container from flex-col to flex-row to match
prototype design where 3 cards are displayed horizontally side by side.

Before: Cards stacked vertically (top to bottom)
After: Cards arranged horizontally (left to right)

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

app/product/page.tsx

@@ -134,8 +134,8 @@ export default function ProductPage() {
               </div>
             </div>
 
-            {/* Product Cards Grid */}
-            <div className="flex flex-col gap-6">
+            {/* Product Cards Grid - Horizontal Layout */}
+            <div className="flex flex-row gap-6">
               {products.map((product) => (
                 <ProductCard
                   key={product.id}