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/app/(dashboard)/teacher/grades/stats/page.tsx

@@ -0,0 +1,139 @@
+import { db } from "@/shared/db"
+import { subjects } from "@/shared/db/schema"
+import { asc } from "drizzle-orm"
+import { getTeacherClasses } from "@/modules/classes/data-access"
+import { getClassGradeStatsWithMeta, getClassRanking } from "@/modules/grades/data-access"
+import { ClassGradeReport } from "@/modules/grades/components/class-grade-report"
+import { ExportButton } from "@/modules/grades/components/export-button"
+import { EmptyState } from "@/shared/components/ui/empty-state"
+import { BarChart3 } from "lucide-react"
+
+export const dynamic = "force-dynamic"
+
+type SearchParams = { [key: string]: string | string[] | undefined }
+
+const getParam = (params: SearchParams, key: string) => {
+  const v = params[key]
+  return Array.isArray(v) ? v[0] : v
+}
+
+export default async function StatsPage({ searchParams }: { searchParams: Promise<SearchParams> }) {
+  const sp = await searchParams
+
+  const classId = getParam(sp, "classId")
+  const subjectId = getParam(sp, "subjectId")
+
+  const [classes, allSubjects] = await Promise.all([
+    getTeacherClasses(),
+    db.query.subjects.findMany({ orderBy: [asc(subjects.order), asc(subjects.name)] }),
+  ])
+
+  if (classes.length === 0) {
+    return (
+      <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
+        <div>
+          <h2 className="text-2xl font-bold tracking-tight">Grade Statistics</h2>
+          <p className="text-muted-foreground">View class grade statistics and rankings.</p>
+        </div>
+        <EmptyState
+          title="No classes"
+          description="You don't have any classes yet."
+          icon={BarChart3}
+          className="border-none shadow-none"
+        />
+      </div>
+    )
+  }
+
+  const targetClassId = classId ?? classes[0].id
+  const targetSubjectId = subjectId && subjectId !== "all" ? subjectId : undefined
+
+  const [stats, ranking] = await Promise.all([
+    getClassGradeStatsWithMeta(targetClassId, targetSubjectId),
+    getClassRanking(targetClassId, targetSubjectId),
+  ])
+
+  const classOptions = classes.map((c) => ({ id: c.id, name: c.name }))
+  const subjectOptions = allSubjects.map((s) => ({ id: s.id, name: s.name }))
+
+  return (
+    <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
+      <div className="flex items-center justify-between">
+        <div>
+          <h2 className="text-2xl font-bold tracking-tight">Grade Statistics</h2>
+          <p className="text-muted-foreground">View class grade statistics and rankings.</p>
+        </div>
+        <ExportButton
+          classId={targetClassId}
+          subjectId={targetSubjectId}
+          variant="outline"
+          label="导出成绩"
+        />
+      </div>
+
+      <StatsClassSelector
+        classes={classOptions}
+        subjects={subjectOptions}
+        currentClassId={targetClassId}
+        currentSubjectId={subjectId ?? "all"}
+      />
+
+      <ClassGradeReport stats={stats} ranking={ranking} />
+    </div>
+  )
+}
+
+function StatsClassSelector({
+  classes,
+  subjects,
+  currentClassId,
+  currentSubjectId,
+}: {
+  classes: Array<{ id: string; name: string }>
+  subjects: Array<{ id: string; name: string }>
+  currentClassId: string
+  currentSubjectId: string
+}) {
+  return (
+    <div className="flex flex-wrap gap-2">
+      {classes.map((c) => (
+        <a
+          key={c.id}
+          href={`/teacher/grades/stats?classId=${c.id}${currentSubjectId !== "all" ? `&subjectId=${currentSubjectId}` : ""}`}
+          className={`rounded-md border px-3 py-1.5 text-sm transition-colors ${
+            c.id === currentClassId
+              ? "border-primary bg-primary text-primary-foreground"
+              : "bg-card hover:bg-accent"
+          }`}
+        >
+          {c.name}
+        </a>
+      ))}
+      <div className="ml-auto flex flex-wrap gap-2">
+        <a
+          href={`/teacher/grades/stats?classId=${currentClassId}`}
+          className={`rounded-md border px-3 py-1.5 text-sm transition-colors ${
+            currentSubjectId === "all"
+              ? "border-primary bg-primary text-primary-foreground"
+              : "bg-card hover:bg-accent"
+          }`}
+        >
+          All Subjects
+        </a>
+        {subjects.map((s) => (
+          <a
+            key={s.id}
+            href={`/teacher/grades/stats?classId=${currentClassId}&subjectId=${s.id}`}
+            className={`rounded-md border px-3 py-1.5 text-sm transition-colors ${
+              s.id === currentSubjectId
+                ? "border-primary bg-primary text-primary-foreground"
+                : "bg-card hover:bg-accent"
+            }`}
+          >
+            {s.name}
+          </a>
+        ))}
+      </div>
+    </div>
+  )
+}