feat(admin): show user subscription plan and token quota in user pages

Expose active subscription summary on user list and detail so operators can see plan type, total/used/remaining tokens without opening billing subscriptions.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/admin/utils/subscription.ts

@@ -0,0 +1,36 @@
+import type { AdminSubscription, PlanDefinition, UserSubscriptionSummary } from '../../types';
+
+export function formatTokenCount(value: number) {
+  return value.toLocaleString('zh-CN');
+}
+
+export function formatTokenQuota(limit: number, used: number) {
+  if (limit === 0) {
+    return `已用 ${formatTokenCount(used)} / 无限`;
+  }
+  const remaining = Math.max(0, limit - used);
+  return `${formatTokenCount(remaining)} / ${formatTokenCount(limit)}（已用 ${formatTokenCount(used)}）`;
+}
+
+export function resolvePlanLabel(planType: string, plans: PlanDefinition[]) {
+  return plans.find((plan) => plan.planType === planType)?.name ?? planType;
+}
+
+export function subscriptionStatusLabel(status: AdminSubscription['status']) {
+  if (status === 'active') return '有效';
+  if (status === 'expired') return '已到期';
+  if (status === 'cancelled') return '已取消';
+  return status;
+}
+
+export function summarizeSubscription(
+  subscription: Pick<UserSubscriptionSummary, 'planType' | 'periodTokensLimit' | 'periodTokensUsed'> | null | undefined,
+  fallbackPlanType?: string,
+) {
+  if (!subscription) {
+    return fallbackPlanType && fallbackPlanType !== 'free'
+      ? `${fallbackPlanType}（无有效订阅）`
+      : '免费 / 无订阅';
+  }
+  return formatTokenQuota(subscription.periodTokensLimit, subscription.periodTokensUsed);
+}