feat(forum,admin): plate follow-pay MVP, sales column, order type tabs

Wire paid plate follow (admin meta + points/balance purchase + AJAX),
re-check plate gate on topics, post list sales column, and order type
subtabs; update gap matrix and admin IA map.

inc/classes/class-aksrt-forum.php

@@ -351,6 +351,7 @@ class AKSRT_Forum {
         add_action('wp_ajax_aksrt_forum_topic_list', [$this, 'ajax_topic_list']);
         add_action('wp_ajax_aksrt_forum_create_topic', [$this, 'ajax_create_topic']);
         add_action('wp_ajax_aksrt_forum_follow_plate', [$this, 'ajax_follow_plate']);
+        add_action('wp_ajax_aksrt_forum_purchase_plate_follow', [$this, 'ajax_purchase_plate_follow']);
         add_action('wp_ajax_aksrt_forum_unlock_topic', [$this, 'ajax_unlock_topic']);
         add_action('wp_ajax_aksrt_forum_purchase_topic', [$this, 'ajax_purchase_topic']);
 
@@ -450,6 +451,10 @@ class AKSRT_Forum {
         $this->board_service()->ajax_follow_plate();
     }
 
+    public function ajax_purchase_plate_follow(): void {
+        $this->board_service()->ajax_purchase_plate_follow();
+    }
+
     public function ajax_unlock_topic(): void {
         $this->topic_service()->ajax_unlock_topic();
     }