feat(messaging,announcements): 前端 UI 集成星标/草稿/置顶/已读回执

- 消息星标：MessageList 卡片星标按钮（乐观更新+回滚）、MessageDetail 头部星标切换
- 消息草稿：MessageCompose 自动保存（2s 防抖）+ 手动保存按钮 + 状态指示器 + 发送后清理草稿
- 公告置顶：AnnouncementCard 管理端置顶按钮、AnnouncementDetail 置顶切换、置顶 Badge
- 公告已读回执：用户端详情页自动标记已读 + 已读/未读 Badge、管理端已读人数显示
- i18n：新增 announcements.meta.readCount 翻译键

src/app/(dashboard)/announcements/[id]/page.tsx

@@ -5,7 +5,7 @@ import { getTranslations } from "next-intl/server"
 
 import { requirePermission } from "@/shared/lib/auth-guard"
 import { Permissions } from "@/shared/types/permissions"
-import { getAnnouncementById } from "@/modules/announcements/data-access"
+import { getAnnouncementById, isAnnouncementReadByUser } from "@/modules/announcements/data-access"
 import { AnnouncementDetail } from "@/modules/announcements/components/announcement-detail"
 
 export const dynamic = "force-dynamic"
@@ -21,15 +21,18 @@ export default async function AnnouncementDetailPage({
   params: Promise<{ id: string }>
 }): Promise<JSX.Element> {
   const { id } = await params
-  await requirePermission(Permissions.ANNOUNCEMENT_READ)
+  const ctx = await requirePermission(Permissions.ANNOUNCEMENT_READ)
 
   const announcement = await getAnnouncementById(id)
   if (!announcement) notFound()
 
+  // 获取当前用户的已读状态
+  const isReadByCurrentUser = await isAnnouncementReadByUser(id, ctx.userId)
+
   return (
     <div className="flex h-full flex-col space-y-8 p-8">
       <AnnouncementDetail
-        announcement={announcement}
+        announcement={{ ...announcement, isReadByCurrentUser }}
         canManage={false}
         backHref="/announcements"
       />