fix(polish): 订单购物车论坛粉边软化 + 论坛付费帖购链路

- 购物车/商品/论坛表面复用 #77 soft recipe（mix 边 + soft ring）
- 论坛 visibility=pay：订单 resource + 余额扣费闭环
- VIP 价/免费解锁 + 购买 CTA/AJAX，复用现有 Order/Credits

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

assets/css/frontend/forum/extras/like-button.css

@@ -14,11 +14,11 @@
 }
 
 .aksrt-forum-reply__like-btn:hover {
-    color: var(--c-primary, #1890ff);
+    color: var(--color-primary);
 }
 
 .aksrt-forum-reply__like-btn.is-active {
-    color: var(--c-primary, #1890ff);
+    color: var(--color-primary);
 }
 
 .aksrt-forum-reply__like-count {