feat: enhance product detail page to support default variant selection from query parameters

src/app/core/services/catalog/catalog.service.ts

@@ -35,9 +35,14 @@ export class CatalogService {
     );
   }
 
-  getProducto(id: number): Observable<ProductDetail> {
+  getProducto(id: number, defaultVariantId?: number): Observable<ProductDetail> {
+    const params =
+      defaultVariantId === undefined
+        ? undefined
+        : new HttpParams({ fromObject: { default_variant: defaultVariantId } });
+
     return this.http
-      .get<ApiResponse<ProductDetail>>(`${this.tenantApiUrl}/productos/${id}`)
+      .get<ApiResponse<ProductDetail>>(`${this.tenantApiUrl}/productos/${id}`, { params })
       .pipe(map((response) => response.data));
   }