feat(product): add reusable Product Experience 2.0

Unify product details modules behind config-driven contracts so teams can
extend UX without changing runtime architecture or bootstrap flow.

Keep backward compatibility with existing product payloads by treating new
media/specification/variant/related structures as optional extensions.

Improve conversion and content discoverability with reusable actions,
typed media rendering, grouped specifications, dynamic variants, and
multi-collection related products.

src/app/core/products/models/product-domain.model.ts

@@ -36,3 +36,14 @@ export interface RelatedProductsQuery {
   categoryID?: number;
   count?: number;
 }
+
+export interface RelatedProductCollection {
+  id: string;
+  title: string;
+  titles?: Record<string, string>;
+  productIDs: number[];
+}
+
+export interface ProductVariantSelection {
+  [groupKey: string]: string;
+}