feat(announcements,messaging): 公告与消息模块审计重构 — i18n + Error Boundary + a11y

- 新增审计报告 docs/architecture/audit/announcements-messages-audit-report.md
- 新增中英双语 i18n 字典 announcements.json / messages.json（11/13 个命名空间）
- 重构所有 announcements 和 messaging 组件接入 next-intl（useTranslations）
- 所有页面 page.tsx 使用 generateMetadata + getTranslations 替代硬编码 metadata
- 新增 7 个 error.tsx 错误边界（4 公告 + 3 消息），统一 EmptyState + i18n + 重试
- a11y 改进：announcement-card / message-list / notification-dropdown 添加 aria-label
- 同步架构图 004 和 005：i18n.messages 清单 + 已知问题修复记录

src/modules/messaging/components/notification-list.tsx

@@ -4,6 +4,7 @@ import { useState } from "react"
 import Link from "next/link"
 import { useRouter } from "next/navigation"
 import { toast } from "sonner"
+import { useTranslations } from "next-intl"
 import { Bell, CheckCheck, MessageSquare, Megaphone, PenTool, GraduationCap } from "lucide-react"
 
 import { Badge } from "@/shared/components/ui/badge"
@@ -22,14 +23,8 @@ const TYPE_ICON: Record<NotificationType, typeof Bell> = {
   grade: GraduationCap,
 }
 
-const TYPE_LABEL: Record<NotificationType, string> = {
-  message: "Message",
-  announcement: "Announcement",
-  homework: "Homework",
-  grade: "Grade",
-}
-
 export function NotificationList({ notifications }: { notifications: Notification[] }) {
+  const t = useTranslations("messages")
   const router = useRouter()
   const [isWorking, setIsWorking] = useState(false)
   const hasUnread = notifications.some((n) => !n.isRead)
@@ -42,10 +37,10 @@ export function NotificationList({ notifications }: { notifications: Notificatio
         toast.success(res.message)
         router.refresh()
       } else {
-        toast.error(res.message || "Failed to mark all as read")
+        toast.error(res.message || t("messages.markReadFailed"))
       }
     } catch {
-      toast.error("Failed to mark all as read")
+      toast.error(t("messages.markReadFailed"))
     } finally {
       setIsWorking(false)
     }
@@ -58,7 +53,7 @@ export function NotificationList({ notifications }: { notifications: Notificatio
         router.refresh()
       }
     } catch {
-      toast.error("Failed to mark as read")
+      toast.error(t("messages.markReadFailed"))
     }
   }
 
@@ -66,21 +61,21 @@ export function NotificationList({ notifications }: { notifications: Notificatio
     <div className="space-y-6">
       <div className="flex flex-wrap items-center justify-between gap-3">
         <div>
-          <h2 className="text-2xl font-bold tracking-tight">Notifications</h2>
-          <p className="text-muted-foreground text-sm">Stay updated on your latest activities.</p>
+          <h2 className="text-2xl font-bold tracking-tight">{t("title.notifications")}</h2>
+          <p className="text-muted-foreground text-sm">{t("description.notifications")}</p>
         </div>
         {hasUnread ? (
           <Button onClick={handleMarkAllRead} disabled={isWorking} variant="outline">
             <CheckCheck className="mr-2 h-4 w-4" />
-            Mark all as read
+            {t("actions.markAllRead")}
           </Button>
         ) : null}
       </div>
 
       {notifications.length === 0 ? (
         <EmptyState
-          title="No notifications"
-          description="You have no notifications yet."
+          title={t("empty.noNotifications")}
+          description={t("empty.noNotificationsDesc")}
           icon={Bell}
           className="h-auto border-none shadow-none"
         />
@@ -95,14 +90,14 @@ export function NotificationList({ notifications }: { notifications: Notificatio
               >
                 <CardContent className="flex items-start gap-3 py-4">
                   <div className="bg-muted flex size-9 shrink-0 items-center justify-center rounded-full">
-                    <Icon className="h-4 w-4" />
+                    <Icon className="h-4 w-4" aria-hidden="true" />
                   </div>
                   <div className="min-w-0 flex-1 space-y-1">
                     <div className="flex items-center gap-2">
                       <span className={cn("text-sm", !n.isRead ? "font-semibold" : "font-medium")}>
                         {n.title}
                       </span>
-                      {!n.isRead ? <Badge variant="default" className="text-xs">New</Badge> : null}
+                      {!n.isRead ? <Badge variant="default" className="text-xs">{t("status.new")}</Badge> : null}
                     </div>
                     {n.content ? (
                       <p className="text-muted-foreground line-clamp-2 text-sm whitespace-pre-wrap">
@@ -111,7 +106,7 @@ export function NotificationList({ notifications }: { notifications: Notificatio
                     ) : null}
                     <div className="flex items-center gap-2 text-xs text-muted-foreground">
                       <Badge variant="outline" className="text-xs">
-                        {TYPE_LABEL[n.type]}
+                        {t(`notificationType.${n.type}`)}
                       </Badge>
                       <span>{formatDate(n.createdAt)}</span>
                       {!n.isRead ? (
@@ -119,13 +114,14 @@ export function NotificationList({ notifications }: { notifications: Notificatio
                           type="button"
                           onClick={() => handleMarkRead(n.id)}
                           className="text-primary hover:underline"
+                          aria-label={t("actions.markRead")}
                         >
-                          Mark as read
+                          {t("actions.markRead")}
                         </button>
                       ) : null}
                       {n.link ? (
                         <Link href={n.link} className="ml-auto text-primary hover:underline">
-                          View
+                          {t("actions.view")}
                         </Link>
                       ) : null}
                     </div>