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/layout/components/site-header.tsx

@@ -3,11 +3,10 @@
 import * as React from "react"
 import Link from "next/link"
 import { usePathname } from "next/navigation"
-import { Bell, Menu, Search } from "lucide-react"
+import { Menu } from "lucide-react"
 import { signOut, useSession } from "next-auth/react"
 
 import { Button } from "@/shared/components/ui/button"
-import { Input } from "@/shared/components/ui/input"
 import { Separator } from "@/shared/components/ui/separator"
 import {
   Breadcrumb,
@@ -26,7 +25,9 @@ import {
     DropdownMenuSeparator,
     DropdownMenuTrigger,
 } from "@/shared/components/ui/dropdown-menu"
+import { GlobalSearch } from "@/shared/components/global-search"
 
+import { NotificationDropdown } from "@/modules/messaging/components/notification-dropdown"
 import { useSidebar } from "./sidebar-provider"
 import { NAV_CONFIG } from "../config/navigation"
 
@@ -110,20 +111,10 @@ export function SiteHeader() {
 
       <div className="flex items-center gap-4">
         {/* Global Search */}
-        <div className="relative hidden md:block">
-          <Search className="text-muted-foreground absolute top-2.5 left-2.5 size-4" />
-          <Input
-            type="search"
-            placeholder="Search... (Cmd+K)"
-            className="w-[200px] pl-9 lg:w-[300px]"
-          />
-        </div>
+        <GlobalSearch className="hidden md:block" />
 
         {/* Notifications */}
-        <Button variant="ghost" size="icon" className="text-muted-foreground">
-          <Bell className="size-5" />
-          <span className="sr-only">Notifications</span>
-        </Button>
+        <NotificationDropdown />
 
         {/* User Nav */}
         <DropdownMenu>