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/modules/lesson-preparation/components/blocks/exercise-block.tsx

@@ -1,6 +1,8 @@
 "use client";
 
 import { useState } from "react";
+import { useRouter } from "next/navigation";
+import { useTranslations } from "next-intl";
 import { useLessonPlanEditor } from "../../hooks/use-lesson-plan-editor";
 import { QuestionBankPicker } from "../question-bank-picker";
 import { InlineQuestionEditor } from "../inline-question-editor";
@@ -10,15 +12,20 @@ import { Plus, Trash2 } from "lucide-react";
 import type {
   ExerciseBlockData,
   ExerciseItem,
+  ExercisePurpose,
 } from "../../types";
 
 interface Props {
   blockId: string;
   data: ExerciseBlockData;
   classes: { id: string; name: string }[];
+  textbookId?: string;
+  chapterId?: string;
 }
 
-export function ExerciseBlock({ blockId, data, classes }: Props) {
+export function ExerciseBlock({ blockId, data, classes, textbookId, chapterId }: Props) {
+  const t = useTranslations("lessonPreparation");
+  const router = useRouter();
   const { updateNode, planId } = useLessonPlanEditor();
   const [showBank, setShowBank] = useState(false);
   const [showInline, setShowInline] = useState(false);
@@ -49,34 +56,34 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
         <select
           value={data.purpose}
           onChange={(e) =>
-            update({ purpose: e.target.value as never })
+            update({ purpose: e.target.value as ExercisePurpose })
           }
           className="border rounded px-2 py-1 text-sm"
         >
-          <option value="class_practice">课堂练习</option>
-          <option value="after_class_homework">课后作业</option>
+          <option value="class_practice">{t("exercise.purpose.class_practice")}</option>
+          <option value="after_class_homework">{t("exercise.purpose.after_class_homework")}</option>
         </select>
       </div>
       {data.items.length === 0 ? (
         <p className="text-on-surface-variant text-sm p-4 text-center border border-dashed rounded">
-          暂无题目，点击下方按钮添加
+          {t("questionBank.empty")}
         </p>
       ) : (
         <div className="space-y-1">
           {data.items.map((item, idx) => (
             <div
-              key={idx}
+              key={item.questionId}
               className="flex items-center gap-2 border rounded p-2"
             >
               <span className="text-xs bg-surface-container-highest px-2 py-0.5 rounded">
-                {item.source === "bank" ? "题库" : "新建"}
+                {item.source === "bank" ? t("questionBank.source.bank") : t("questionBank.source.inline")}
               </span>
               <span className="text-sm flex-1 truncate">
                 {item.source === "bank"
-                  ? `题目 ${item.questionId.slice(0, 8)}`
-                  : "课案内新建题目"}
+                  ? t("questionBank.questionId", { id: item.questionId.slice(0, 8) })
+                  : t("questionBank.inlineQuestion")}
               </span>
-              <span className="text-xs">{item.score}分</span>
+              <span className="text-xs">{t("questionBank.score", { score: item.score })}</span>
               <button onClick={() => removeItem(idx)}>
                 <Trash2 className="w-3 h-3 text-error" />
               </button>
@@ -91,7 +98,7 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
           onClick={() => setShowBank(true)}
         >
           <Plus className="w-3 h-3 mr-1" />
-          从题库添加
+          {t("questionBank.fromBank")}
         </Button>
         <Button
           variant="outline"
@@ -99,18 +106,18 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
           onClick={() => setShowInline(true)}
         >
           <Plus className="w-3 h-3 mr-1" />
-          新建题目
+          {t("questionBank.inlineNew")}
         </Button>
         {data.publishedAssignmentId ? (
           <div className="flex items-center gap-2 text-sm">
             <span className="bg-tertiary-container/20 text-tertiary px-2 py-1 rounded">
-              已发布为作业
+              {t("status.publishedAsHomework")}
             </span>
             <a
               href="/teacher/homework"
               className="text-primary underline"
             >
-              查看
+              {t("action.viewHomework")}
             </a>
           </div>
         ) : (
@@ -120,7 +127,7 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
               size="sm"
               onClick={() => setShowPublish(true)}
             >
-              发布为作业
+              {t("action.publish")}
             </Button>
           )
         )}
@@ -134,6 +141,8 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
       )}
       {showInline && (
         <InlineQuestionEditor
+          textbookId={textbookId}
+          chapterId={chapterId}
           onAdd={(item) => {
             addItems([item]);
             setShowInline(false);
@@ -147,7 +156,7 @@ export function ExerciseBlock({ blockId, data, classes }: Props) {
           blockId={blockId}
           classes={classes}
           onClose={() => setShowPublish(false)}
-          onPublished={() => window.location.reload()}
+          onPublished={() => router.refresh()}
         />
       )}
     </div>