feat: improve audit exports and admin analytics

ai_knowledge_base_v2/apps/user-client/src/components/SessionQuota.vue

@@ -3,6 +3,7 @@ import { Layers3, LoaderCircle } from "@lucide/vue";
 import { computed } from "vue";
 
 import type { UserEntitlementSummary } from "../types/api";
+import { formatDate } from "../utils/dateTime";
 
 const props = defineProps<{
   used: number;
@@ -26,11 +27,6 @@ const usageText = computed(() => {
   if (displayLimit.value <= 0) return "今日不可用";
   return `今日 ${displayUsed.value}/${displayLimit.value} 次`;
 });
-function formatDate(value?: string | null) {
-  if (!value) return "";
-  const date = new Date(value);
-  return Number.isNaN(date.getTime()) ? value : date.toLocaleDateString("zh-CN");
-}
 const guidanceText = computed(() => {
   if (props.entitlement?.lifecycleStatus === "expired_fallback") {
     return `原${props.entitlement.previousPlanName ? `“${props.entitlement.previousPlanName}”` : "权益"}已于 ${formatDate(props.entitlement.previousExpiredAt)} 到期，当前已自动切换为${props.entitlement.name}，已有对话与回顾仍会保留。`;