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/categories/categories.controller.ts

@@ -173,4 +173,13 @@ export class PublicCategoriesController {
   list(@Param('host') host: string, @Query() query: ListCategoriesDto) {
     return this.service.listPublic(host, query);
   }
+
+  @Get('by-slug/:slug')
+  getBySlug(
+    @Param('host') host: string,
+    @Param('slug') slug: string,
+    @Query() query: ListCategoriesDto,
+  ) {
+    return this.service.getPublicBySlug(host, slug, query.entityType);
+  }
 }