feat(admin): native plate moderators, product variants, discount term fields

Add WP-native ops UI without SPA: plate moderator list/application review
meta box, product SKU variants editor meta box, and shop_discount taxonomy
add/edit form fields. No admin build artifacts included.

functions.php

@@ -298,6 +298,16 @@ if (is_admin() && class_exists('AKSRT_Admin_Shop_Controller')) {
 if (is_admin() && class_exists('AKSRT_Product_Meta_Box')) {
     AKSRT_Product_Meta_Box::get_instance()->init();
 }
+// 商品原生变体 meta box
+if (is_admin() && class_exists('AKSRT_Product_Variants_Meta_Box')) {
+    AKSRT_Product_Variants_Meta_Box::get_instance()->init();
+}
+
+// 论坛版块版主 meta box
+if (is_admin() && class_exists('AKSRT_Plate_Meta_Box')) {
+    AKSRT_Plate_Meta_Box::get_instance()->init();
+}
+
 
 // 商品评价/评分系统
 if (class_exists('AKSRT_Product_Review')) {