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/app/(dashboard)/teacher/diagnostic/student/[studentId]/page.tsx

@@ -1,3 +1,4 @@
+import type { JSX } from "react"
 import { notFound } from "next/navigation"
 import { Stethoscope } from "lucide-react"
 import { getAuthContext } from "@/shared/lib/auth-guard"
@@ -15,7 +16,7 @@ export default async function StudentDiagnosticPage({
   params,
 }: {
   params: Promise<{ studentId: string }>
-}) {
+}): Promise<JSX.Element> {
   const { studentId } = await params
   const ctx = await getAuthContext()
 
@@ -27,16 +28,15 @@ export default async function StudentDiagnosticPage({
     notFound()
   }
 
-  const [summary, reports] = await Promise.all([
+  const [summary, reports, classStats] = await Promise.all([
     getStudentMasterySummary(studentId),
     getDiagnosticReports({ studentId }),
+    getKnowledgePointStats(),
   ])
 
   // 班级平均掌握度（用于雷达图对比）
   let classAverageMastery: MasteryRadarPoint[] | undefined
   if (summary) {
-    // 通过学生所在班级获取班级平均
-    const classStats = await getKnowledgePointStats()
     classAverageMastery = classStats.map((k) => ({
       knowledgePoint: k.knowledgePointName,
       student: 0,
@@ -47,10 +47,10 @@ export default async function StudentDiagnosticPage({
   return (
     <div className="h-full flex-1 flex-col space-y-8 p-8 md:flex">
       <div>
-        <h2 className="flex items-center gap-2 text-2xl font-bold tracking-tight">
-          <Stethoscope className="h-6 w-6" />
+        <h1 className="flex items-center gap-2 text-2xl font-bold tracking-tight">
+          <Stethoscope className="h-6 w-6" aria-hidden="true" />
           Student Diagnostic
-        </h2>
+        </h1>
         <p className="text-muted-foreground">
           Knowledge point mastery analysis and diagnostic reports.
         </p>