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- Remove the now-superseded root prompt files (moved into Ai data/)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/Header.tsx

@@ -15,6 +15,7 @@ import {
 } from "./icons";
 import { headerNavLinks } from "@/data/site";
 import { CUSTOMER_PORTAL_URL } from "@/lib/config";
+import { categoryHref } from "@/lib/slug";
 import type { CategoryNode } from "@/lib/types";
 
 const socialLinks = [
@@ -91,7 +92,7 @@ export default function Header({ categoryColumns }: { categoryColumns: CategoryN
                     {categoryColumns.map((col) => (
                       <div key={col.id} className="min-w-[180px]">
                         <Link
-                          href={`/products?category=${col.slug}`}
+                          href={categoryHref(col)}
                           className="block font-bold text-ink text-sm mb-2.5 hover:text-brand transition-colors"
                         >
                           {col.nameFa}
@@ -100,7 +101,7 @@ export default function Header({ categoryColumns }: { categoryColumns: CategoryN
                           {col.children.map((sub) => (
                             <li key={sub.id}>
                               <Link
-                                href={`/products?category=${sub.slug}`}
+                                href={categoryHref(sub)}
                                 className="text-[13px] text-body hover:text-gold-dark transition-colors"
                               >
                                 {sub.nameFa}
@@ -182,7 +183,7 @@ export default function Header({ categoryColumns }: { categoryColumns: CategoryN
                   {categoryColumns.map((col) => (
                     <div key={col.id}>
                       <Link
-                        href={`/products?category=${col.slug}`}
+                        href={categoryHref(col)}
                         className="block text-sm font-bold text-ink"
                         onClick={() => setMobileOpen(false)}
                       >
@@ -192,7 +193,7 @@ export default function Header({ categoryColumns }: { categoryColumns: CategoryN
                         {col.children.map((sub) => (
                           <li key={sub.id}>
                             <Link
-                              href={`/products?category=${sub.slug}`}
+                              href={categoryHref(sub)}
                               className="text-sm text-body"
                               onClick={() => setMobileOpen(false)}
                             >