fix(frontend): route the VIP points-exchange entry through the custom currency name

/user/vip/ 档位购买卡下方的入口横条仍硬编码「积分兑换会员」，而后台
「积分配置 → 自定义货币名称」改名后不跟随。上一轮改名只覆盖了兑换弹窗
标题与会员弹窗内入口，页面自身的入口横条是另一处服务端渲染，漏改了。

入口横条（inc/helpers/aksrt-vip.php）
- aksrt_get_vip_points_exchange_entry_html 改取已加载的
  catalog.currency_name，回退 Settings::get_currency_name() 再回退「积分」

同一页面上其余漏改的兑换文案一并收口，命名与入口/弹窗保持一致：
- VipServiceModal：积分不足提示 → {货币名}不足，暂时无法兑换
- VipServicePurchase.exchange_with_points：兑换未启用 / 兑换无效 /
  不足三处 WP_Error、流水说明、订单备注（%1$s兑换会员 %2$d %1$s。）
  currency_name 在此单独解析，get_catalog 内的局部变量不在该作用域
- LedgerPresentation：vip_points_exchange 流水原因标签

契约测试新增源断言，并用两个 PHP harness 做运行时断言：入口横条
（改名后 / 已是会员不输出 / 缺 key 回退）与弹窗（余额充足 / 不足两分支）。

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

src/Content/VipServiceModal.php

@@ -250,7 +250,9 @@ trait VipServiceModal {
         // （参考主题源码写作 `!$min_val > $user_points`，因运算符优先级恒假，
         //  此处按其原意取真实比较，保证提示分支可达。）
         if ($min_points > $user_points) {
-            $form = '<div class="mt20"><div class="badg c-red btn-block">' . esc_html__('积分不足，暂时无法兑换', 'aksrt') . '</div></div>';
+            $form = '<div class="mt20"><div class="badg c-red btn-block">'
+                . esc_html(sprintf(__('%s不足，暂时无法兑换', 'aksrt'), $currency))
+                . '</div></div>';
         } else {
             $form = '<div class="mt20">'
                 . '<input type="hidden" name="product_id" value="' . $first_package_id . '">'

src/Content/VipServicePurchase.php

@@ -737,12 +737,20 @@ trait VipServicePurchase {
             return new \WP_Error('aksrt_need_login', __('请先登录后再兑换。', 'aksrt'), ['status' => 401]);
         }
         $catalog = $this->get_catalog($user_id);
+        // 兑换相关文案（错误提示 / 订单备注 / 流水说明）统一跟随自定义货币名称
+        // （后台「积分配置 → 自定义货币名称」），catalog 已带出 currency_name。
+        $currency_name = (string) ($catalog['currency_name'] ?? '');
+        if ($currency_name === '') {
+            $currency_name = class_exists('\AKSRT\Settings\Settings')
+                ? \AKSRT\Settings\Settings::get_currency_name()
+                : __('积分', 'aksrt');
+        }
         if (array_key_exists('credits_enabled', $catalog) && empty($catalog['credits_enabled'])) {
 			return new \WP_Error('aksrt_points_disabled', __('积分功能未启用', 'aksrt'), ['status' => 400]);
         }
         $points_ex = is_array($catalog['points_exchange'] ?? null) ? $catalog['points_exchange'] : [];
         if (empty($points_ex['enabled'])) {
-            return new \WP_Error('aksrt_points_exchange_disabled', __('积分兑换会员未启用', 'aksrt'), ['status' => 400]);
+            return new \WP_Error('aksrt_points_exchange_disabled', sprintf(__('%s兑换会员未启用', 'aksrt'), $currency_name), ['status' => 400]);
         }
 
         $match = null;
@@ -775,12 +783,12 @@ trait VipServicePurchase {
             $pkg_unit = 'day';
         }
         if ($cost <= 0) {
-            return new \WP_Error('aksrt_invalid_price', __('兑换积分无效', 'aksrt'), ['status' => 400]);
+            return new \WP_Error('aksrt_invalid_price', sprintf(__('兑换%s无效', 'aksrt'), $currency_name), ['status' => 400]);
         }
 
         $balance = (int) ($catalog['user_points'] ?? 0);
         if ($balance < $cost) {
-			return new \WP_Error('aksrt_points_insufficient', __('积分不足，暂时无法兑换', 'aksrt'), [
+			return new \WP_Error('aksrt_points_insufficient', sprintf(__('%s不足，暂时无法兑换', 'aksrt'), $currency_name), [
                 'status' => 402,
                 'balance' => $balance,
                 'cost' => $cost,
@@ -855,7 +863,7 @@ trait VipServicePurchase {
 			$operation_key,
             'vip_points_exchange',
             ['type' => 'order', 'key' => $order_number],
-            sprintf(__('积分兑换会员 · %s', 'aksrt'), (string) ($match['title'] ?? '')),
+            sprintf(__('%s兑换会员 · %s', 'aksrt'), $currency_name, (string) ($match['title'] ?? '')),
             $user_id,
             ['level' => $level, 'days' => $days, 'package_id' => $package_id],
 			static function () use ($is_new_order, $repo, $order_number, $operation_key, $user_id, $package_id, $cost, $note) {
@@ -879,7 +887,8 @@ trait VipServicePurchase {
 				}
 				$paid = \AKSRT\Payment\Order::get_instance()->update_status($order_number, \AKSRT\Payment\Order::STATUS_PAID, [
 					'payment_method' => 'points',
-					'note' => sprintf(__('积分兑换会员 %d 积分。', 'aksrt'), $cost),
+					// 订单备注同样跟随自定义货币名称（后台「积分配置 → 自定义货币名称」）。
+					'note' => sprintf(__('%1$s兑换会员 %2$d %1$s。', 'aksrt'), $currency_name, $cost),
 					'require_transition' => true,
 				]);
 				return $paid ? true : new \WP_Error('aksrt_order_confirm_failed', __('兑换确认失败', 'aksrt'), ['status' => 500]);

src/Ledger/LedgerPresentation.php

@@ -8,6 +8,16 @@ namespace AKSRT\Ledger;
 defined('ABSPATH') || exit;
 
 final class LedgerPresentation {
+	/**
+	 * 自定义货币名称，为空时回退"积分"（后台「积分配置 → 自定义货币名称」）。
+	 * 兑换类流水的说明文案跟随它，与收银台/用户中心保持同一命名。
+	 */
+	private static function points_name(): string {
+		return class_exists('\AKSRT\Settings\Settings')
+			? \AKSRT\Settings\Settings::get_currency_name()
+			: __('积分', 'aksrt');
+	}
+
 	public static function reason_label(string $reason): string {
 		$labels = [
 			'admin_adjustment' => __('管理员调整', 'aksrt'),
@@ -34,7 +44,7 @@ final class LedgerPresentation {
 			'transfer' => __('用户转账', 'aksrt'),
 			'tip' => __('用户赞赏', 'aksrt'),
 			'verify_application' => __('认证申请费用', 'aksrt'),
-			'vip_points_exchange' => __('积分兑换会员', 'aksrt'),
+			'vip_points_exchange' => sprintf(__('%s兑换会员', 'aksrt'), self::points_name()),
 			'withdraw_hold' => __('提现冻结', 'aksrt'),
 			'withdraw_refund' => __('提现退回', 'aksrt'),
 		];