fix: 修复公告关闭功能 - 当次关闭与永久关闭区分

问题：不管选择"当次关闭"还是"永久关闭"，都会永久关闭公告

修复：
- 当次关闭：使用 sessionStorage + pageToken
  - pageToken 基于 performance.timeOrigin 生成
  - 刷新页面后 token 变化，公告重新显示
- 永久关闭：使用 localStorage
  - 持久化存储，刷新/重开后不再显示

修改文件：
- app-frontend/src/layouts/AppLayout.vue
- templates/index.html

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app-frontend/src/layouts/AppLayout.vue

@@ -29,6 +29,56 @@ const announcementOpen = ref(false)
 const announcement = ref(null)
 const announcementLoading = ref(false)
 
+const announcementPageToken = (() => {
+  try {
+    const timeOrigin = window.performance?.timeOrigin
+    if (typeof timeOrigin === 'number' && Number.isFinite(timeOrigin)) return String(timeOrigin)
+  } catch {
+    // ignore
+  }
+  return String(Date.now())
+})()
+
+function announcementOnceKey(announcementId) {
+  return `announcement_closed_once_${announcementId}`
+}
+
+function announcementPermanentKey(announcementId) {
+  return `announcement_closed_${announcementId}`
+}
+
+function wasAnnouncementClosedOnce(announcementId) {
+  try {
+    return window.sessionStorage.getItem(announcementOnceKey(announcementId)) === announcementPageToken
+  } catch {
+    return false
+  }
+}
+
+function wasAnnouncementClosedPermanently(announcementId) {
+  try {
+    return window.localStorage.getItem(announcementPermanentKey(announcementId)) === '1'
+  } catch {
+    return false
+  }
+}
+
+function markAnnouncementClosedOnce(announcementId) {
+  try {
+    window.sessionStorage.setItem(announcementOnceKey(announcementId), announcementPageToken)
+  } catch {
+    // ignore
+  }
+}
+
+function markAnnouncementClosedPermanently(announcementId) {
+  try {
+    window.localStorage.setItem(announcementPermanentKey(announcementId), '1')
+  } catch {
+    // ignore
+  }
+}
+
 const feedbackOpen = ref(false)
 const feedbackTab = ref('new')
 const feedbackSubmitting = ref(false)
@@ -329,8 +379,8 @@ async function loadAnnouncement() {
     const ann = data?.announcement
     if (!ann?.id) return
 
-    const sessionKey = `announcement_closed_${ann.id}`
-    if (window.sessionStorage.getItem(sessionKey) === '1') return
+    if (wasAnnouncementClosedPermanently(ann.id)) return
+    if (wasAnnouncementClosedOnce(ann.id)) return
 
     announcement.value = ann
     announcementOpen.value = true
@@ -343,7 +393,7 @@ async function loadAnnouncement() {
 
 function closeAnnouncementOnce() {
   const ann = announcement.value
-  if (ann?.id) window.sessionStorage.setItem(`announcement_closed_${ann.id}`, '1')
+  if (ann?.id) markAnnouncementClosedOnce(ann.id)
   announcementOpen.value = false
 }
 
@@ -353,6 +403,7 @@ async function dismissAnnouncementPermanently() {
     announcementOpen.value = false
     return
   }
+  markAnnouncementClosedPermanently(ann.id)
   try {
     const res = await dismissAnnouncement(ann.id)
     if (res?.success) ElMessage.success('已永久关闭')