fix(vip): render points exchange description

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

tests/widget-system/vip-settings-structured-harness.php

@@ -155,6 +155,7 @@ namespace {
 		],
 		'vip_2_renew_product' => [],
 		'pay_vip_points_exchange_s' => true,
+		'pay_vip_points_exchange_desc' => '<p>积分兑换说明</p>',
 		'pay_vip_points_exchange_product' => [
 			['points' => 800, 'level' => 1, 'time' => 30, 'unit' => 'day'],
 			['points' => 9000, 'level' => 2, 'time' => 'Permanent'],