Redesign product detail page and fix icon/cart reactivity bugs

- SingleProduct.vue: rebuild gallery/header/action bar as a self-scrolling
  layout with a sticky photo, solid-on-scroll header matching PageBar, and
  a full-screen image preview (blurred overlay, centered thumbnail strip)
- Add GallerySlider.vue: pointer-based swipe carousel isolated in an
  LTR subtree, fixing RTL/transform sign mismatch that caused slide jumps
- Fix Icon.vue: icon was read into a plain ref once at setup and never
  updated on prop change; switch to computed so icon swaps (e.g. cart
  qty stepper trash/minus toggle) actually re-render
- Fix quantity stepper DOM order in SingleProduct.vue/CartItem.vue so
  plus/minus render correctly under RTL flex
- prisma/assign-downloaded-images.js: seed real product photos (FEATURED/
  FEATURED_MOBILE/GALLERY/GALLERY_MOBILE) onto the 5 placeholder products

apps/user-app-v2/dist/index.html

@@ -9,8 +9,8 @@
     <meta name="background-color" content="#1C2D56" />
     <meta content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no" name="viewport" />
     <title>طلای منتزر</title>
-    <script type="module" crossorigin src="/assets/index-CmYEpHK9.js"></script>
-    <link rel="stylesheet" crossorigin href="/assets/index-W391hScl.css">
+    <script type="module" crossorigin src="/assets/index-gciDsUQi.js"></script>
+    <link rel="stylesheet" crossorigin href="/assets/index-D-jEuKqG.css">
   <link rel="manifest" href="/manifest.webmanifest"></head>
   <body style="background-color: #1C2D56">
     <div class="bg-white w-screen h-screen fixed"></div>