Include product category URLs in sitemaps and document by-slug lookup.

Adds /products/category/{slug} to default sitemap generation and a public categories/by-slug endpoint for storefront category pages.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/business-settings/business-settings.types.ts

@@ -128,6 +128,7 @@ export type SitemapStaticPageConfig = {
 
 export type SitemapPathTemplatesConfig = {
   product?: string;
+  productCategory?: string;
   blog?: string;
   portfolio?: string;
   storeItemByProduct?: string;