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/announcements/components/announcement-list.tsx

@@ -3,7 +3,8 @@
 import { useMemo, useState } from "react"
 import Link from "next/link"
 import { useRouter } from "next/navigation"
-import { Plus } from "lucide-react"
+import { Plus, Megaphone } from "lucide-react"
+import { useTranslations } from "next-intl"
 
 import { Button } from "@/shared/components/ui/button"
 import { EmptyState } from "@/shared/components/ui/empty-state"
@@ -14,20 +15,12 @@ import {
   SelectTrigger,
   SelectValue,
 } from "@/shared/components/ui/select"
-import { Megaphone } from "lucide-react"
 
 import { AnnouncementCard } from "./announcement-card"
 import type { Announcement, AnnouncementStatus } from "../types"
 
 type Filter = "all" | AnnouncementStatus
 
-const FILTER_OPTIONS: { value: Filter; label: string }[] = [
-  { value: "all", label: "All" },
-  { value: "published", label: "Published" },
-  { value: "draft", label: "Draft" },
-  { value: "archived", label: "Archived" },
-]
-
 export function AnnouncementList({
   announcements,
   canManage,
@@ -41,9 +34,17 @@ export function AnnouncementList({
   detailHrefBuilder?: (id: string) => string
   initialStatus?: Filter
 }) {
+  const t = useTranslations("announcements")
   const router = useRouter()
   const [filter, setFilter] = useState<Filter>(initialStatus ?? "all")
 
+  const filterOptions: { value: Filter; label: string }[] = [
+    { value: "all", label: t("filter.all") },
+    { value: "published", label: t("filter.published") },
+    { value: "draft", label: t("filter.draft") },
+    { value: "archived", label: t("filter.archived") },
+  ]
+
   const filtered = useMemo(() => {
     if (filter === "all") return announcements
     return announcements.filter((a) => a.status === filter)
@@ -62,10 +63,10 @@ export function AnnouncementList({
       <div className="flex flex-wrap items-center justify-between gap-3">
         <Select value={filter} onValueChange={handleFilterChange}>
           <SelectTrigger className="w-[180px]">
-            <SelectValue placeholder="Filter by status" />
+            <SelectValue placeholder={t("filter.placeholder")} />
           </SelectTrigger>
           <SelectContent>
-            {FILTER_OPTIONS.map((opt) => (
+            {filterOptions.map((opt) => (
               <SelectItem key={opt.value} value={opt.value}>
                 {opt.label}
               </SelectItem>
@@ -76,7 +77,7 @@ export function AnnouncementList({
           <Button asChild>
             <Link href={createHref}>
               <Plus className="mr-2 h-4 w-4" />
-              New Announcement
+              {t("actions.new")}
             </Link>
           </Button>
         ) : null}
@@ -84,11 +85,11 @@ export function AnnouncementList({
 
       {filtered.length === 0 ? (
         <EmptyState
-          title="No announcements"
+          title={t("empty.noAnnouncements")}
           description={
             announcements.length === 0
-              ? "There are no announcements yet."
-              : "No announcements match the current filter."
+              ? t("empty.noAnnouncementsDesc")
+              : t("empty.noMatch")
           }
           icon={Megaphone}
           className="h-auto border-none shadow-none"