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/publish-service.ts

@@ -4,13 +4,11 @@ import { eq } from "drizzle-orm";
 import { createId } from "@paralleldrive/cuid2";
 
 import { db } from "@/shared/db";
-import {
-  lessonPlans,
-  examQuestions,
-} from "@/shared/db/schema";
+import { lessonPlans } from "@/shared/db/schema";
 import { createQuestionWithRelations } from "@/modules/questions/data-access";
-import { persistExamDraft } from "@/modules/exams/data-access";
+import { persistExamDraft, addExamQuestions } from "@/modules/exams/data-access";
 import { createHomeworkAssignment } from "@/modules/homework/data-access-write";
+import { getStudentIdsByClassIds } from "@/modules/classes/data-access";
 import { normalizeDocument } from "./data-access";
 import type { LessonPlanDocument, ExerciseBlockData } from "./types";
 
@@ -29,20 +27,6 @@ interface PublishResult {
   updatedContent: LessonPlanDocument;
 }
 
-// 查询班级学生列表（避免直接依赖 classes 模块的内部表）
-async function getStudentIdsByClassIds(
-  classIds: string[],
-): Promise<string[]> {
-  if (classIds.length === 0) return [];
-  const { inArray } = await import("drizzle-orm");
-  const { classEnrollments } = await import("@/shared/db/schema");
-  const rows = await db
-    .select({ studentId: classEnrollments.studentId })
-    .from(classEnrollments)
-    .where(inArray(classEnrollments.classId, classIds));
-  return rows.map((r) => r.studentId);
-}
-
 export async function publishLessonPlanHomework(
   input: PublishInput,
 ): Promise<PublishResult> {
@@ -80,9 +64,7 @@ export async function publishLessonPlanHomework(
     throw new Error("该练习块已发布，请使用'重新发布'");
 
   // 3. inline 题目入库，替换占位 ID
-  const newContent: LessonPlanDocument = JSON.parse(
-    JSON.stringify(plan.content),
-  );
+  const newContent: LessonPlanDocument = structuredClone(plan.content);
   const newBlock = newContent.nodes.find((b) => b.id === input.blockId);
   if (!newBlock || newBlock.type !== "exercise")
     throw new Error("练习块不存在");
@@ -122,17 +104,15 @@ export async function publishLessonPlanHomework(
     scheduledAt: undefined,
     description: `来自课案：${plan.title}`,
   });
-  // 插入 examQuestions
-  if (newData.items.length > 0) {
-    await db.insert(examQuestions).values(
-      newData.items.map((it, i) => ({
-        examId,
-        questionId: it.questionId,
-        score: it.score,
-        order: i,
-      })),
-    );
-  }
+  // 插入 examQuestions（通过 exams data-access 跨模块接口）
+  await addExamQuestions(
+    examId,
+    newData.items.map((it, i) => ({
+      questionId: it.questionId,
+      score: it.score,
+      order: i,
+    })),
+  );
 
   // 5. 下发作业
   const assignmentId = createId();