SEO-friendly id-based URLs, sitemap/robots, and homepage category banners

- Replace legacy DB-slug URLs with /products/{id}/{fa-slug},
  /products/category/{id}/{fa-slug}, and /blog/{id}/{fa-slug}, backed by
  the new by-id API endpoints and a Persian slugify helper
- Add /sitemap.xml (index) + /sitemap-main.xml + /sitemap-products.xml
  and /robots.txt pointing to it
- Register the three-banner-row slot in the static-image-slots catalog
- Replace the homepage category carousel with a 3-column linkable
  ThreeBanners section wired to that slot
- Remove the now-superseded root prompt files (moved into Ai data/)

src/components/SearchBox.tsx

@@ -5,6 +5,7 @@ import Link from "next/link";
 import { getProducts } from "@/lib/api";
 import type { ApiProduct } from "@/lib/types";
 import { formatToman } from "@/lib/format";
+import { productHref } from "@/lib/slug";
 import { SearchIcon } from "./icons";
 
 const MIN_QUERY_LENGTH = 3;
@@ -92,7 +93,7 @@ export default function SearchBox({
             results.map((product) => (
               <Link
                 key={product.id}
-                href={`/products/${product.slug}`}
+                href={productHref(product)}
                 onClick={() => setOpen(false)}
                 className="flex items-center gap-3 p-3 hover:bg-surface transition-colors border-b border-line last:border-0"
               >