Fix product links, equalize card heights, and switch to IRANYekan

- Resolve product cards from group endpoints (store-specials,
  brand-groups) that only return a productId, not a slug, via a new
  /products/id/[id] route backed by GET /products/by-id/{id} — clicking
  these was previously falling back to a name search instead of the
  detail page.
- Derive discount price/percent generically in normalizeProduct so any
  source with real old/new prices shows it, even without an explicit
  discount field from the API.
- Product cards and the detail page buy-box: show the discount badge
  beside the old (struck-through) price, current price alone on its
  own line, matching the reference design.
- Equalize product card heights within a carousel row (Swiper's own
  CSS doesn't stretch slides to the tallest sibling in slidesPerView:
  "auto" + freeMode mode) so the add-to-cart button lines up across
  cards regardless of whether a card has a discount line.
- Featured categories: 110px images with no border/radius, matching
  the site's other category card treatment.
- Replace Vazirmatn with the client's IRANYekan font files — light
  weight for body text, bold weight for headings only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/app/layout.tsx

@@ -1,15 +1,23 @@
 import type { Metadata } from "next";
-import { Vazirmatn, Syne } from "next/font/google";
+import { Syne } from "next/font/google";
+import localFont from "next/font/local";
 import "./globals.css";
 import { TopBar } from "@/components/home/TopBar";
 import { Header } from "@/components/home/Header";
 import { Footer } from "@/components/home/Footer";
 import { getBusinessInfo, getCategories, getCategoryTree } from "@/lib/meshkee";
 
-const vazirmatn = Vazirmatn({
-  variable: "--font-vazirmatn",
-  subsets: ["arabic", "latin"],
-  weight: ["400", "500", "600", "700"],
+// Body text — headings use the bold weight instead, see globals.css.
+const iranyekan = localFont({
+  variable: "--font-iranyekan",
+  src: "../../public/fonts/iranyekanweblightfanum.woff",
+  weight: "400",
+});
+
+const iranyekanBold = localFont({
+  variable: "--font-iranyekan-bold",
+  src: "../../public/fonts/iranyekanwebboldfanum.woff",
+  weight: "700",
 });
 
 const syne = Syne({
@@ -34,7 +42,7 @@ export default async function RootLayout({ children }: LayoutProps<"/">) {
     <html
       lang="fa"
       dir="rtl"
-      className={`${vazirmatn.variable} ${syne.variable} h-full antialiased`}
+      className={`${iranyekan.variable} ${iranyekanBold.variable} ${syne.variable} h-full antialiased`}
     >
       <body className="min-h-full flex flex-col">
         <TopBar />