feat: 新增备课模块并修复全模块 P0/P1/P2 缺陷

主要变更:

- 新增 lesson-preparation 模块: 备课编辑器、节点编辑、AI 建议、知识点选择、版本历史、作业发布

- 新增 shared 通用组件: charts/question-bank-filters/schedule-list/ui (chip-nav/filter-bar/page-header/stat-card/stat-item)

- 新增 student/admin 端 loading.tsx 与 error.tsx, 优化加载与错误态体验

- 新增 teacher/lesson-plans 页面 (列表/新建/编辑)

- 新增 drizzle 迁移 0002_tiny_lionheart 及 snapshot

- 新增 textbooks/schema.ts 与 exams/utils/normalize-structure.ts

- 修复 Tiptap v3 SSR hydration 崩溃 (rich-text-block immediatelyRender: false)

- 重构多模块 data-access/actions/组件, 修复权限校验与类型规范

- 同步架构文档 004/005 反映新增模块、导出、依赖关系

- 归档 bugs/* 测试报告与 e2e 测试脚本 (admin/parent/student/teacher web_test)

src/modules/dashboard/components/student-dashboard/student-stats-grid.tsx

@@ -1,19 +1,8 @@
-import Link from "next/link"
-import { BookOpen, PenTool, TriangleAlert, Trophy, TrendingUp } from "lucide-react"
+import { PenTool, TriangleAlert, Trophy, TrendingUp } from "lucide-react"
 
-import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui/card"
-import { cn } from "@/shared/lib/utils"
+import { StatCard } from "@/shared/components/ui/stat-card"
 import type { StudentRanking } from "@/modules/homework/types"
 
-type Stat = {
-  title: string
-  value: string
-  description: string
-  icon: typeof BookOpen
-  href: string
-  color?: string
-}
-
 export function StudentStatsGrid({
   dueSoonCount,
   overdueCount,
@@ -25,57 +14,44 @@ export function StudentStatsGrid({
   gradedCount: number
   ranking: StudentRanking | null
 }) {
-  const stats: Stat[] = [
-    {
-      title: "Average Score",
-      value: ranking ? `${Math.round(ranking.percentage)}%` : "-",
-      description: ranking ? "Overall performance" : "No grades yet",
-      icon: TrendingUp,
-      href: "/student/learning/assignments",
-      color: "text-blue-500",
-    },
-    {
-      title: "Class Rank",
-      value: ranking ? `${ranking.rank}/${ranking.classSize}` : "-",
-      description: ranking ? "Current position" : "No ranking yet",
-      icon: Trophy,
-      href: "/student/learning/assignments",
-      color: "text-purple-500",
-    },
-    {
-      title: "Due Soon",
-      value: String(dueSoonCount),
-      description: "Next 7 days",
-      icon: PenTool,
-      href: "/student/learning/assignments",
-      color: dueSoonCount > 0 ? "text-orange-500" : undefined,
-    },
-    {
-      title: "Overdue",
-      value: String(overdueCount),
-      description: "Needs attention",
-      icon: TriangleAlert,
-      href: "/student/learning/assignments",
-      color: overdueCount > 0 ? "text-red-500" : undefined,
-    },
-  ]
-
   return (
     <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">
-      {stats.map((stat) => (
-        <Link key={stat.title} href={stat.href}>
-          <Card className="hover:bg-muted/50 transition-colors cursor-pointer h-full">
-            <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
-              <CardTitle className="text-sm font-medium">{stat.title}</CardTitle>
-              <stat.icon className={cn("h-4 w-4 text-muted-foreground", stat.color)} />
-            </CardHeader>
-            <CardContent>
-              <div className={cn("text-2xl font-bold tabular-nums", stat.color)}>{stat.value}</div>
-              <div className="text-xs text-muted-foreground">{stat.description}</div>
-            </CardContent>
-          </Card>
-        </Link>
-      ))}
+      <StatCard
+        title="Average Score"
+        value={ranking ? `${Math.round(ranking.percentage)}%` : "-"}
+        description={ranking ? "Overall performance" : "No grades yet"}
+        icon={TrendingUp}
+        href="/student/learning/assignments"
+        color="text-blue-500"
+        valueClassName={ranking ? "text-blue-500 tabular-nums" : "tabular-nums"}
+      />
+      <StatCard
+        title="Class Rank"
+        value={ranking ? `${ranking.rank}/${ranking.classSize}` : "-"}
+        description={ranking ? "Current position" : "No ranking yet"}
+        icon={Trophy}
+        href="/student/learning/assignments"
+        color="text-purple-500"
+        valueClassName={ranking ? "text-purple-500 tabular-nums" : "tabular-nums"}
+      />
+      <StatCard
+        title="Due Soon"
+        value={String(dueSoonCount)}
+        description="Next 7 days"
+        icon={PenTool}
+        href="/student/learning/assignments"
+        color={dueSoonCount > 0 ? "text-orange-500" : undefined}
+        valueClassName={dueSoonCount > 0 ? "text-orange-500 tabular-nums" : "tabular-nums"}
+      />
+      <StatCard
+        title="Overdue"
+        value={String(overdueCount)}
+        description="Needs attention"
+        icon={TriangleAlert}
+        href="/student/learning/assignments"
+        color={overdueCount > 0 ? "text-red-500" : undefined}
+        valueClassName={overdueCount > 0 ? "text-red-500 tabular-nums" : "tabular-nums"}
+      />
     </div>
   )
 }