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/grades/components/grade-distribution-chart.tsx

@@ -0,0 +1,138 @@
+"use client"
+
+import { PieChart as PieChartIcon } from "lucide-react"
+import { Bar, BarChart, CartesianGrid, Cell, XAxis, YAxis } from "recharts"
+
+import {
+  Card,
+  CardContent,
+  CardDescription,
+  CardHeader,
+  CardTitle,
+} from "@/shared/components/ui/card"
+import {
+  ChartContainer,
+  ChartTooltip,
+  ChartTooltipContent,
+} from "@/shared/components/ui/chart"
+import { EmptyState } from "@/shared/components/ui/empty-state"
+import type { GradeDistributionResult } from "@/modules/grades/types"
+
+const BUCKET_COLORS: Record<string, string> = {
+  "90-100": "hsl(142, 71%, 45%)",
+  "80-89": "hsl(217, 91%, 60%)",
+  "70-79": "hsl(43, 96%, 56%)",
+  "60-69": "hsl(25, 95%, 53%)",
+  "<60": "hsl(0, 84%, 60%)",
+}
+
+const chartConfig = {
+  count: { label: "Students", color: "hsl(var(--primary))" },
+}
+
+interface GradeDistributionChartProps {
+  data: GradeDistributionResult | null
+}
+
+export function GradeDistributionChart({ data }: GradeDistributionChartProps) {
+  if (!data || data.totalCount === 0) {
+    return (
+      <Card>
+        <CardHeader>
+          <CardTitle className="flex items-center gap-2">
+            <PieChartIcon className="h-4 w-4" />
+            Score Distribution
+          </CardTitle>
+          <CardDescription>
+            Number of students in each score range (normalized to 0-100).
+          </CardDescription>
+        </CardHeader>
+        <CardContent>
+          <EmptyState
+            icon={PieChartIcon}
+            title="No distribution data"
+            description="Select a class and subject to view score distribution."
+            className="border-none h-60"
+          />
+        </CardContent>
+      </Card>
+    )
+  }
+
+  const chartData = data.buckets.map((b) => ({
+    label: b.label,
+    count: b.count,
+    percentage:
+      data.totalCount > 0
+        ? Math.round((b.count / data.totalCount) * 1000) / 10
+        : 0,
+  }))
+
+  return (
+    <Card>
+      <CardHeader>
+        <CardTitle className="flex items-center gap-2">
+          <PieChartIcon className="h-4 w-4" />
+          Score Distribution
+        </CardTitle>
+        <CardDescription>
+          {data.totalCount} grade record{data.totalCount === 1 ? "" : "s"} across
+          score ranges.
+        </CardDescription>
+      </CardHeader>
+      <CardContent>
+        <ChartContainer config={chartConfig} className="h-[280px] w-full">
+          <BarChart
+            data={chartData}
+            margin={{ left: 8, right: 8, top: 8, bottom: 8 }}
+          >
+            <CartesianGrid
+              vertical={false}
+              strokeDasharray="4 4"
+              strokeOpacity={0.4}
+            />
+            <XAxis
+              dataKey="label"
+              tickLine={false}
+              axisLine={false}
+              tickMargin={8}
+            />
+            <YAxis
+              allowDecimals={false}
+              tickLine={false}
+              axisLine={false}
+              width={32}
+            />
+            <ChartTooltip
+              content={
+                <ChartTooltipContent
+                  className="w-[200px]"
+                  formatter={(payload: unknown) => {
+                    const item = (payload as { payload?: (typeof chartData)[number] })?.payload
+                    if (!item) return null
+                    return (
+                      <div className="flex w-full flex-col gap-0.5">
+                        <span className="text-sm font-medium">
+                          {item.label}: {item.count} student
+                          {item.count === 1 ? "" : "s"}
+                        </span>
+                        <span className="text-xs text-muted-foreground">
+                          {item.percentage}% of total
+                        </span>
+                      </div>
+                    )
+                  }}
+                />
+              }
+            />
+            <Bar dataKey="count" radius={[4, 4, 0, 0]}>
+              {chartData.map((entry) => (
+                <Cell key={entry.label} fill={BUCKET_COLORS[entry.label]} />
+              ))}
+            </Bar>
+          </BarChart>
+        </ChartContainer>
+      </CardContent>
+    </Card>
+  )
+}