refactor(announcements,messaging,notifications): V1+V2 审计重构 — i18n 命名空间独立 + 通知标题 i18n 化 + 服务端过滤 + 编排下沉 + 表单错误展示 + 架构图同步

V1 改进（已完成）:
- P0-4/P1-4/P1-5: 通知组件和 CRUD Action 从 messaging 迁移至 notifications 模块
- P1-5: 新增 getMessagesPageData / getAdminAnnouncementsPageData 编排函数
- P1-6: announcements schema 添加 superRefine 条件校验
- P1-7: 新增 useMessageSearch hook（防抖 + 请求竞态取消）+ 客户端分页 UI
- P1-9: deleteMessage 事务化
- P2-11: 全模块 trackEvent 埋点
- 全模块 i18n 接入 + Error Boundary + a11y 改进

V2 改进（本次完成）:
- V2-P0-1: 通知 i18n 命名空间独立（notifications.json），useTranslations 从 "messages" 切换到 "notifications"
- V2-P0-2: 公告/消息通知标题 i18n 化，Server Action 中使用 getTranslations 生成通知标题
- V2-P1-1: AnnouncementList 纯服务端过滤，移除客户端 useState/useMemo
- V2-P1-2: MessageList 客户端过滤仅在初始数据时执行，搜索结果由服务端按 tab 过滤
- V2-P1-3: 消息详情页编排下沉，新增 getMessageDetailPageData 编排函数
- V2-P1-4: 表单服务端校验错误展示（fieldErrors + aria-invalid）
- V2-P2-1: 轮询间隔常量化（POLL_INTERVAL_MS）
- V2-P2-2: 架构图同步（004 + 005）

src/shared/i18n/messages/zh-CN/announcements.json

@@ -80,7 +80,11 @@
     "noAnnouncementsDesc": "目前还没有任何公告。",
     "noMatch": "当前筛选条件下暂无公告。",
     "deleteTitle": "删除公告",
-    "deleteDesc": "此操作将永久删除"{title}"。"
+    "deleteDesc": "此操作将永久删除公告{title}。"
+  },
+  "notification": {
+    "publishedTitle": "新公告：{title}",
+    "publishedContent": "您有一条新公告，请及时查看。"
   },
   "error": {
     "loadFailed": "公告加载失败",

src/shared/i18n/messages/zh-CN/messages.json

@@ -4,13 +4,11 @@
     "detail": "消息详情",
     "compose": "撰写消息",
     "reply": "回复",
-    "newMessage": "新消息",
-    "notifications": "通知"
+    "newMessage": "新消息"
   },
   "description": {
     "list": "管理收件箱并随时掌握通知动态。",
-    "compose": "向其他用户发送消息。",
-    "notifications": "随时了解最新动态。"
+    "compose": "向其他用户发送消息。"
   },
   "tabs": {
     "inbox": "收件箱",
@@ -20,14 +18,10 @@
     "compose": "撰写",
     "reply": "回复",
     "delete": "删除",
-    "markRead": "标记已读",
-    "markAllRead": "全部标记已读",
     "send": "发送",
     "sending": "发送中...",
     "cancel": "取消",
-    "back": "返回",
-    "viewAll": "查看全部通知",
-    "view": "查看"
+    "back": "返回"
   },
   "form": {
     "to": "收件人",
@@ -51,12 +45,6 @@
     "noSubject": "（无主题）",
     "readAt": "阅读于 {date}"
   },
-  "notificationType": {
-    "message": "消息",
-    "announcement": "公告",
-    "homework": "作业",
-    "grade": "成绩"
-  },
   "search": {
     "placeholder": "按主题或内容搜索消息...",
     "noResults": "未找到匹配的消息"
@@ -66,26 +54,24 @@
     "inboxEmptyDesc": "您还没有收到任何消息。",
     "sentEmpty": "无已发送消息",
     "sentEmptyDesc": "您还没有发送任何消息。",
-    "noNotifications": "暂无通知",
-    "noNotificationsDesc": "您还没有任何通知。",
-    "noNotificationsDropdown": "暂无通知",
     "deleteTitle": "删除消息",
-    "deleteDesc": "此操作将永久删除消息"{subject}"。"
+    "deleteDesc": "此操作将永久删除消息{subject}。"
   },
   "messages": {
     "sent": "消息已发送",
     "deleted": "消息已删除",
     "markedRead": "已标记为已读",
-    "allMarkedRead": "全部已标记为已读",
-    "notificationMarkedRead": "通知已标记为已读",
     "sendSelf": "不能给自己发送消息",
     "sendFailed": "发送消息失败",
     "deleteFailed": "删除失败",
-    "markReadFailed": "标记已读失败",
     "notFound": "消息不存在",
     "invalidId": "消息 ID 无效",
     "selectRecipient": "请选择收件人"
   },
+  "notification": {
+    "messageTitle": "新消息：{subject}",
+    "messageTitleNoSubject": "新消息"
+  },
   "error": {
     "loadFailed": "消息加载失败",
     "loadFailedDesc": "抱歉，加载消息时发生了意外错误。请稍后重试。",

src/shared/i18n/messages/zh-CN/notifications.json

@@ -0,0 +1,39 @@
+{
+  "title": {
+    "list": "通知",
+    "dropdown": "通知"
+  },
+  "description": {
+    "list": "随时了解最新动态。"
+  },
+  "actions": {
+    "markRead": "标记已读",
+    "markAllRead": "全部标记已读",
+    "viewAll": "查看全部通知",
+    "view": "查看"
+  },
+  "type": {
+    "message": "消息",
+    "announcement": "公告",
+    "homework": "作业",
+    "grade": "成绩"
+  },
+  "status": {
+    "new": "新"
+  },
+  "empty": {
+    "noNotifications": "暂无通知",
+    "noNotificationsDesc": "您还没有任何通知。",
+    "noNotificationsDropdown": "暂无通知"
+  },
+  "messages": {
+    "allMarkedRead": "全部已标记为已读",
+    "notificationMarkedRead": "通知已标记为已读",
+    "markReadFailed": "标记已读失败"
+  },
+  "error": {
+    "loadFailed": "通知加载失败",
+    "loadFailedDesc": "抱歉，加载通知时发生了意外错误。请稍后重试。",
+    "retry": "重试"
+  }
+}