feat(lesson-preparation): 备课模块审计重构 — 跨模块解耦 + i18n + 纯函数抽取 + 错误边界

P0-1 跨模块直查修复：publish-service 不再直查 examQuestions 表，新增 exams/data-access.addExamQuestions 接口，复用 classes/data-access.getStudentIdsByClassIds

P0-2 i18n 接入：新增 zh-CN/en 翻译文件，注册 lessonPreparation 命名空间，17 个组件改造为 useTranslations/getTranslations

P1 纯函数抽取：lib/document-migration.ts（类型守卫替代 as 断言）、lib/node-summary.ts（翻译函数注入）、lib/rf-mappers.ts

P1 错误边界+骨架屏：新增 LessonPlanErrorBoundary 和 4 个 Skeleton 组件

P1 Block 注册表：新增 config/block-registry.tsx（BlockRenderer 组件），node-edit-panel 重构为配置驱动渲染

P1 其他修复：exercise-block 改用 router.refresh()，node-editor/lesson-node 复用 lib/ 纯函数

架构图同步：更新 004 和 005 文档

Refs: docs/architecture/audit/lesson-preparation-audit-report.md

src/app/(dashboard)/teacher/lesson-plans/page.tsx

@@ -1,6 +1,7 @@
 import type { JSX } from "react"
 import Link from "next/link"
 import { Plus } from "lucide-react"
+import { getTranslations } from "next-intl/server"
 import { Button } from "@/shared/components/ui/button"
 import { getAuthContext } from "@/shared/lib/auth-guard"
 import { getLessonPlans } from "@/modules/lesson-preparation/data-access"
@@ -10,6 +11,7 @@ import { LessonPlanList } from "@/modules/lesson-preparation/components/lesson-p
 export const dynamic = "force-dynamic"
 
 export default async function LessonPlansPage(): Promise<JSX.Element> {
+  const t = await getTranslations("lessonPreparation")
   const ctx = await getAuthContext()
 
   const [items, subjects] = await Promise.all([
@@ -21,15 +23,15 @@ export default async function LessonPlansPage(): Promise<JSX.Element> {
     <div className="p-6 space-y-4">
       <div className="flex justify-between items-center">
         <div>
-          <h1 className="text-2xl font-bold tracking-tight">My Lesson Plans</h1>
+          <h1 className="text-2xl font-bold tracking-tight">{t("title.list")}</h1>
           <p className="text-muted-foreground">
-            Manage your lesson preparation and teaching plans.
+            {t("description.list")}
           </p>
         </div>
         <Button asChild>
           <Link href="/teacher/lesson-plans/new">
             <Plus className="h-4 w-4 mr-2" aria-hidden="true" />
-            New Lesson Plan
+            {t("action.new")}
           </Link>
         </Button>
       </div>