feat(product-detail): ProductDescription section + strict discount guard + category types

- app/components/product/ProductDescription.tsx: new below-fold section
  with a "توضیحات محصول" heading, whitespace-pre-line so multi-line seller
  copy (Instagram scrapes, victorwear WooCommerce imports) renders with
  its bullet-list line breaks preserved. Renders on both mobile and
  desktop; nothing shown when the product has no description.
- app/components/product/ProductInfo.tsx: removed the collapsed
  single-<p> mobile description; the new section replaces it.
- app/components/product/ProductDetailView.tsx: pricingOf now hides the
  discount when discount_price >= price (was only hiding when equal),
  so a stale row where the discount price accidentally matches or
  exceeds the base can never render as a fake promo. Mounts
  ProductDescription just above the mobile Contact button and reviews.
- app/components/product/index.ts: export ProductDescription.
- src/api/types/models/index.ts: ProductCategory now carries readonly
  parentId / parentName so the two-step category picker can build the
  parent→sub tree from a flat category list without an extra fetch.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

app/components/product/ProductDescription.tsx

@@ -0,0 +1,33 @@
+import { AlignRight } from "lucide-react";
+
+interface ProductDescriptionProps {
+  description?: string | null;
+}
+
+/**
+ * Full product description block. Preserves the seller's line breaks (bullet
+ * lists from Instagram/WooCommerce imports come in as `\n`-separated lines),
+ * with a proper heading so it reads as its own section on the detail page.
+ *
+ * Renders nothing when no description is set — the section header shouldn't
+ * appear on products the seller hasn't filled out yet.
+ */
+export function ProductDescription({ description }: ProductDescriptionProps) {
+  const body = (description || "").trim();
+  if (!body) return null;
+
+  return (
+    <section className="w-full px-4 lg:px-0 my-6">
+      <div className="flex items-center gap-2 mb-3">
+        <AlignRight size={18} className="text-BLACK" />
+        <h2 className="text-B16 lg:text-B20 font-bold">توضیحات محصول</h2>
+      </div>
+      <div
+        className="text-R14 lg:text-[15px] leading-8 text-BLACK2 whitespace-pre-line"
+        dir="rtl"
+      >
+        {body}
+      </div>
+    </section>
+  );
+}

app/components/product/ProductDetailView.tsx

@@ -3,6 +3,7 @@ import {
   ProductImageCarousel,
   ProductActions,
   ProductInfo,
+  ProductDescription,
   ColorSelector,
   SizeSelector,
   ContactButton,
@@ -138,7 +139,12 @@ export const ProductDetailView = memo(function ProductDetailView({
     discountPrice:
       v?.discountPrice &&
       v.discountPrice !== "0" &&
-      Number(v.discountPrice) !== Number(v.price)
+      // Only surface as a "discount" when it's a real saving. A value equal
+      // to (or somehow larger than) `price` is stale/mis-entered state, not a
+      // discount — sellers occasionally end up with matching numbers when
+      // they set "no discount" on edit, and rendering a strikethrough on that
+      // fakes a promo the seller didn't intend.
+      Number(v.discountPrice) < Number(v.price)
         ? v.discountPrice
         : null,
   });
@@ -713,9 +719,10 @@ export const ProductDetailView = memo(function ProductDetailView({
         </div>
       </div>
 
-      {/* Full-width below the fold: contact, reviews, similar */}
+      {/* Full-width below the fold: description, contact, reviews, similar */}
       {productActiveStatus && (
         <>
+          <ProductDescription description={product.description} />
           {!isOwner && (
             <div className="lg:hidden">
               <ContactButton product={product} />

app/components/product/ProductInfo.tsx

@@ -25,6 +25,8 @@ export const ProductInfo = ({
       ) : null}
       <p className="text-B18 lg:text-[26px] font-bold">{product.title}</p>
     </div>
-    <p className="text-R12 text-GRAY">{product.description}</p>
+    {/* Description moved into the dedicated ProductDescription section below
+        the buy actions so multi-line seller copy renders with line breaks and
+        appears on desktop too. */}
   </div>
 );

app/components/product/index.ts

@@ -2,6 +2,7 @@ export { ProductHeader } from "./ProductHeader";
 export { ProductImageCarousel } from "./ProductImageCarousel";
 export { ProductActions } from "./ProductActions";
 export { ProductInfo } from "./ProductInfo";
+export { ProductDescription } from "./ProductDescription";
 export { ColorSelector } from "./ColorSelector";
 export { SizeSelector } from "./SizeSelector";
 export { ContactButton } from "./ContactButton";

src/api/types/models/index.ts

@@ -3525,6 +3525,18 @@ export interface ProductCategory {
      * @memberof ProductCategory
      */
     description?: string | null;
+    /**
+     * UUID of this category's parent (null for top-level parents).
+     * @type {string}
+     * @memberof ProductCategory
+     */
+    readonly parentId?: string | null;
+    /**
+     * Human-readable name of the parent (null for top-level parents).
+     * @type {string}
+     * @memberof ProductCategory
+     */
+    readonly parentName?: string | null;
 }
 /**
  *