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/messaging/components/message-compose.tsx

@@ -0,0 +1,146 @@
+"use client"
+
+import { useState } from "react"
+import { useRouter } from "next/navigation"
+import { toast } from "sonner"
+import { ArrowLeft, Send } from "lucide-react"
+
+import { Button } from "@/shared/components/ui/button"
+import { Card, CardContent, CardFooter, CardHeader, CardTitle } from "@/shared/components/ui/card"
+import { Input } from "@/shared/components/ui/input"
+import { Label } from "@/shared/components/ui/label"
+import { Textarea } from "@/shared/components/ui/textarea"
+import {
+  Select,
+  SelectContent,
+  SelectItem,
+  SelectTrigger,
+  SelectValue,
+} from "@/shared/components/ui/select"
+
+import { sendMessageAction } from "../actions"
+import type { RecipientOption } from "../types"
+
+export function MessageCompose({
+  recipients,
+  parentMessageId,
+  defaultReceiverId,
+  defaultSubject,
+  backHref = "/messages",
+}: {
+  recipients: RecipientOption[]
+  parentMessageId?: string
+  defaultReceiverId?: string
+  defaultSubject?: string
+  backHref?: string
+}) {
+  const router = useRouter()
+  const [isWorking, setIsWorking] = useState(false)
+  const [receiverId, setReceiverId] = useState(defaultReceiverId ?? "")
+
+  const handleSubmit = async (formData: FormData) => {
+    if (!receiverId) {
+      toast.error("Please select a recipient")
+      return
+    }
+    formData.set("receiverId", receiverId)
+    if (parentMessageId) {
+      formData.set("parentMessageId", parentMessageId)
+    }
+
+    setIsWorking(true)
+    try {
+      const res = await sendMessageAction(null, formData)
+      if (res.success) {
+        toast.success(res.message)
+        router.push("/messages")
+        router.refresh()
+      } else {
+        toast.error(res.message || "Failed to send message")
+      }
+    } catch {
+      toast.error("Failed to send message")
+    } finally {
+      setIsWorking(false)
+    }
+  }
+
+  return (
+    <Card>
+      <CardHeader>
+        <div className="flex items-center gap-2">
+          <Button asChild variant="ghost" size="icon">
+            <a href={backHref}>
+              <ArrowLeft className="h-4 w-4" />
+            </a>
+          </Button>
+          <CardTitle>{parentMessageId ? "Reply" : "New Message"}</CardTitle>
+        </div>
+      </CardHeader>
+      <CardContent>
+        <form action={handleSubmit} className="space-y-6">
+          <div className="grid gap-2">
+            <Label htmlFor="receiverId">To</Label>
+            <Select value={receiverId} onValueChange={setReceiverId} disabled={!!defaultReceiverId}>
+              <SelectTrigger>
+                <SelectValue placeholder="Select a recipient" />
+              </SelectTrigger>
+              <SelectContent>
+                {recipients.map((r) => (
+                  <SelectItem key={r.id} value={r.id}>
+                    {r.name}
+                    {r.role ? ` (${r.role})` : ""}
+                  </SelectItem>
+                ))}
+              </SelectContent>
+            </Select>
+            <input type="hidden" name="receiverId" value={receiverId} />
+          </div>
+
+          <div className="grid gap-2">
+            <Label htmlFor="subject">Subject</Label>
+            <Input
+              id="subject"
+              name="subject"
+              placeholder="Message subject"
+              defaultValue={defaultSubject ?? ""}
+              maxLength={255}
+            />
+          </div>
+
+          <div className="grid gap-2">
+            <Label htmlFor="content">Content</Label>
+            <Textarea
+              id="content"
+              name="content"
+              placeholder="Write your message..."
+              className="min-h-[200px]"
+              required
+            />
+          </div>
+
+          <CardFooter className="justify-end gap-2 px-0">
+            <Button
+              type="button"
+              variant="outline"
+              onClick={() => router.push(backHref)}
+              disabled={isWorking}
+            >
+              Cancel
+            </Button>
+            <Button type="submit" disabled={isWorking || !receiverId}>
+              {isWorking ? (
+                "Sending..."
+              ) : (
+                <>
+                  <Send className="mr-2 h-4 w-4" />
+                  Send
+                </>
+              )}
+            </Button>
+          </CardFooter>
+        </form>
+      </CardContent>
+    </Card>
+  )
+}