feat: 完成 P1 全部功能 + 修复 proxy 导出 + 切换 MySQL 端口至 14013

## P1 功能（20 项）
- 站内消息系统、家长仪表盘、学生考勤管理
- Excel 导入导出、用户批量导入、成绩导出
- 排课规则+自动排课+课表调整
- 成绩趋势+对比分析、密码安全策略、速率限制
- 数据变更日志、文件预览+存储策略、全文检索
- 依赖审计集成 CI、数据库定时备份、E2E 测试完善
- 通知偏好管理

## 基础设施修复
- src/proxy.ts: 将 middleware 导出重命名为 proxy（Next.js 16 要求）
- .env: MySQL 端口从 13002 切换至 14013
- scripts/create-db.ts: 新增数据库初始化脚本

## 架构文档同步
- 004_architecture_impact_map.md 和 005_architecture_data.json
  完整记录所有新增表、模块、路由、权限、依赖关系

src/modules/announcements/data-access.ts

@@ -0,0 +1,120 @@
+import "server-only"
+
+import { cache } from "react"
+import { and, desc, eq } from "drizzle-orm"
+
+import { db } from "@/shared/db"
+import { announcements, users } from "@/shared/db/schema"
+import type {
+  Announcement,
+  AnnouncementStatus,
+  AnnouncementType,
+  GetAnnouncementsParams,
+} from "./types"
+
+const toIso = (d: Date | null | undefined): string | null =>
+  d ? d.toISOString() : null
+
+const mapRow = (
+  row: {
+    id: string
+    title: string
+    content: string
+    type: "school" | "grade" | "class"
+    status: "draft" | "published" | "archived"
+    targetGradeId: string | null
+    targetClassId: string | null
+    authorId: string
+    authorName: string | null
+    publishedAt: Date | null
+    createdAt: Date
+    updatedAt: Date
+  }
+): Announcement => ({
+  id: row.id,
+  title: row.title,
+  content: row.content,
+  type: row.type,
+  status: row.status,
+  targetGradeId: row.targetGradeId,
+  targetClassId: row.targetClassId,
+  authorId: row.authorId,
+  authorName: row.authorName,
+  publishedAt: toIso(row.publishedAt),
+  createdAt: toIso(row.createdAt) as string,
+  updatedAt: toIso(row.updatedAt) as string,
+})
+
+export const getAnnouncements = cache(
+  async (params?: GetAnnouncementsParams): Promise<Announcement[]> => {
+    try {
+      const page = Math.max(1, params?.page ?? 1)
+      const pageSize = Math.max(1, params?.pageSize ?? 20)
+      const offset = (page - 1) * pageSize
+
+      const conditions = []
+      if (params?.status) {
+        conditions.push(eq(announcements.status, params.status as AnnouncementStatus))
+      }
+      if (params?.type) {
+        conditions.push(eq(announcements.type, params.type as AnnouncementType))
+      }
+
+      const rows = await db
+        .select({
+          id: announcements.id,
+          title: announcements.title,
+          content: announcements.content,
+          type: announcements.type,
+          status: announcements.status,
+          targetGradeId: announcements.targetGradeId,
+          targetClassId: announcements.targetClassId,
+          authorId: announcements.authorId,
+          authorName: users.name,
+          publishedAt: announcements.publishedAt,
+          createdAt: announcements.createdAt,
+          updatedAt: announcements.updatedAt,
+        })
+        .from(announcements)
+        .leftJoin(users, eq(users.id, announcements.authorId))
+        .where(conditions.length > 0 ? and(...conditions) : undefined)
+        .orderBy(desc(announcements.createdAt))
+        .limit(pageSize)
+        .offset(offset)
+
+      return rows.map(mapRow)
+    } catch {
+      return []
+    }
+  }
+)
+
+export const getAnnouncementById = cache(
+  async (id: string): Promise<Announcement | null> => {
+    try {
+      const [row] = await db
+        .select({
+          id: announcements.id,
+          title: announcements.title,
+          content: announcements.content,
+          type: announcements.type,
+          status: announcements.status,
+          targetGradeId: announcements.targetGradeId,
+          targetClassId: announcements.targetClassId,
+          authorId: announcements.authorId,
+          authorName: users.name,
+          publishedAt: announcements.publishedAt,
+          createdAt: announcements.createdAt,
+          updatedAt: announcements.updatedAt,
+        })
+        .from(announcements)
+        .leftJoin(users, eq(users.id, announcements.authorId))
+        .where(eq(announcements.id, id))
+        .limit(1)
+
+      return row ? mapRow(row) : null
+    } catch {
+      return null
+    }
+  }
+)