feat(announcements,messaging,notifications): 实现所有长期问题 — SSE 实时推送 + 通知日志持久化 + 优先级/归档 + 消息星标/草稿 + 公告已读回执/置顶 + 分类筛选/桌面推送 + 测试覆盖

P1-8 通知实时推送（SSE）:
- 新增 /api/notifications/stream SSE 端点（15 秒推送，5 分钟超时）
- 新增 useNotificationStream Hook（SSE + 轮询降级）
- NotificationDropdown 改用 SSE 实时推送

P2-12 测试覆盖:
- notifications/dispatcher.test.ts（6 个测试，渠道选择逻辑）
- notifications/channels/in-app-channel.test.ts（9 个测试，类型映射）
- messaging/schema.test.ts（34 个测试，Zod 校验）
- tests/e2e/messages.spec.ts（消息模块 E2E 测试）
- vitest.unit.config.ts 添加 server-only stub

P2-13a 通知发送日志持久化:
- 新增 notification_logs 表（userId/title/channel/status/messageId/error/sentAt）
- logNotificationSend 改为 async 写入 DB（失败降级 console）
- dispatcher 传递 payload 用于持久化

P2-13b 通知优先级和归档:
- messageNotifications 表新增 priority（low/normal/high/urgent）和 isArchived 字段
- getNotifications 支持归档和优先级筛选
- 新增 archiveNotificationAction
- NotificationList 显示优先级 Badge 和归档按钮

P2-13c 消息星标和草稿:
- messages 表新增 isStarred 字段
- 新增 message_drafts 表
- 新增 toggleMessageStar + 草稿 CRUD Server Actions
- 新增 5 个草稿 data-access 函数

P2-13d 公告已读回执和置顶:
- announcements 表新增 isPinned 字段
- 新增 announcement_reads 表（唯一索引保证幂等）
- 新增 toggleAnnouncementPinAction + markAnnouncementAsReadAction
- getAnnouncements 排序置顶优先

P2-13e 通知分类筛选和桌面推送:
- NotificationList 添加按类型筛选按钮组
- 新增 useDesktopNotifications Hook（浏览器 Notification API）
- NotificationDropdown 集成桌面推送（新通知触发）

架构图同步:
- 004 和 005 均已更新（新增表、Action、Hook、组件描述）

src/modules/announcements/actions.ts

@@ -25,6 +25,9 @@ import {
   deleteAnnouncementById,
   publishAnnouncementById,
   archiveAnnouncementById,
+  toggleAnnouncementPin,
+  markAnnouncementAsRead,
+  getAnnouncementReadStatusForUser,
 } from "./data-access"
 import type { GetAnnouncementsParams, Announcement } from "./types"
 
@@ -325,6 +328,68 @@ export async function archiveAnnouncementAction(id: string): Promise<ActionState
   }
 }
 
+// ---------------------------------------------------------------------------
+// V2-P2-13d: 公告置顶 Server Action
+// ---------------------------------------------------------------------------
+
+export async function toggleAnnouncementPinAction(id: string): Promise<ActionState<string>> {
+  try {
+    await requirePermission(Permissions.ANNOUNCEMENT_MANAGE)
+
+    await toggleAnnouncementPin(id)
+    revalidatePath("/admin/announcements")
+    revalidatePath("/announcements")
+
+    void trackEvent({
+      event: "announcement.pin_toggled",
+      targetId: id,
+      targetType: "announcement",
+    })
+
+    return { success: true, message: "Pin status toggled" }
+  } catch (e) {
+    return handleActionError(e)
+  }
+}
+
+// ---------------------------------------------------------------------------
+// V2-P2-13d: 公告已读标记 Server Action
+// ---------------------------------------------------------------------------
+
+export async function markAnnouncementAsReadAction(announcementId: string): Promise<ActionState<string>> {
+  try {
+    const ctx = await requirePermission(Permissions.ANNOUNCEMENT_READ)
+
+    await markAnnouncementAsRead(announcementId, ctx.userId)
+
+    void trackEvent({
+      event: "announcement.marked_read",
+      userId: ctx.userId,
+      targetId: announcementId,
+      targetType: "announcement",
+    })
+
+    return { success: true, message: "Announcement marked as read" }
+  } catch (e) {
+    return handleActionError(e)
+  }
+}
+
+/**
+ * 批量获取公告已读状态（用于列表页标记已读/未读）。
+ */
+export async function getAnnouncementReadStatusAction(
+  announcementIds: string[]
+): Promise<ActionState<Record<string, boolean>>> {
+  try {
+    const ctx = await requirePermission(Permissions.ANNOUNCEMENT_READ)
+    const statusMap = await getAnnouncementReadStatusForUser(announcementIds, ctx.userId)
+    return { success: true, data: Object.fromEntries(statusMap) }
+  } catch (e) {
+    return handleActionError(e)
+  }
+}
+
 export async function getAnnouncementsAction(
   params?: GetAnnouncementsParams
 ): Promise<ActionState<Announcement[]>> {