feat(shop): wire storefront buy path to server cart

Connect product options/add-cart, server cart checkout payloads,
favorite/rebuy/receipt REST, and order-center actions without
localStorage dual-read or hardcoded cart/orders URL hacks.

inc/classes/admin/class-aksrt-admin-shop-controller.php

@@ -346,6 +346,18 @@ class AKSRT_Admin_Shop_Controller extends AKSRT_Admin_Controller_Base {
             'permission_callback' => [$this, 'check_logged_in_permission'],
         ]);
 
+        register_rest_route(self::API_NAMESPACE, '/shop/frontend/orders/(?P<order_number>[A-Za-z0-9]+)/rebuy', [
+            'methods'             => 'POST',
+            'callback'            => [$this, 'rebuy_frontend_order'],
+            'permission_callback' => [$this, 'check_logged_in_permission'],
+        ]);
+
+        register_rest_route(self::API_NAMESPACE, '/shop/frontend/products/(?P<id>\d+)/favorite', [
+            'methods'             => 'POST',
+            'callback'            => [$this, 'toggle_frontend_product_favorite'],
+            'permission_callback' => [$this, 'check_logged_in_permission'],
+        ]);
+
         register_rest_route(self::API_NAMESPACE, '/shop/after-sale/reasons', [
             'methods'             => 'GET',
             'callback'            => [$this, 'get_after_sale_reasons'],