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/config/block-registry.tsx

@@ -0,0 +1,110 @@
+import type { ReactElement } from "react";
+import type {
+  BlockType,
+  ExerciseBlockData,
+  RichTextBlockData,
+  TextStudyBlockData,
+} from "../types";
+import { RichTextBlock } from "../components/blocks/rich-text-block";
+import { ExerciseBlock } from "../components/blocks/exercise-block";
+import { TextStudyBlock } from "../components/blocks/text-study-block";
+import { ReflectionBlock } from "../components/blocks/reflection-block";
+
+/**
+ * Block 注册表：配置驱动渲染。
+ * 新增 Block 类型只需在此注册，无需修改 NodeEditPanel。
+ */
+
+export interface BlockRenderProps {
+  blockId: string;
+  data: RichTextBlockData | ExerciseBlockData | TextStudyBlockData;
+  textbookId?: string;
+  chapterId?: string;
+  classes?: { id: string; name: string }[];
+  onUpdate: (data: RichTextBlockData | ExerciseBlockData | TextStudyBlockData) => void;
+}
+
+export interface BlockRegistryEntry {
+  /** 是否为富文本类（共享 RichTextBlock 编辑器） */
+  isRichText?: boolean;
+}
+
+const RICH_TEXT_TYPES: BlockType[] = [
+  "objective",
+  "key_point",
+  "import",
+  "new_teaching",
+  "consolidation",
+  "summary",
+  "homework",
+  "blackboard",
+  "rich_text",
+];
+
+/**
+ * Block 注册表元数据（用于查询 isRichText 等属性）。
+ * 组件渲染由 BlockRenderer 统一处理，避免在 render 中动态获取组件引用。
+ */
+export const BLOCK_REGISTRY: Record<BlockType, BlockRegistryEntry> = {
+  objective: { isRichText: true },
+  key_point: { isRichText: true },
+  import: { isRichText: true },
+  new_teaching: { isRichText: true },
+  consolidation: { isRichText: true },
+  summary: { isRichText: true },
+  homework: { isRichText: true },
+  blackboard: { isRichText: true },
+  rich_text: { isRichText: true },
+  exercise: {},
+  text_study: {},
+  reflection: {},
+};
+
+export function isRichTextBlock(type: BlockType): boolean {
+  return RICH_TEXT_TYPES.includes(type);
+}
+
+/**
+ * 静态 Block 渲染组件。
+ * 根据 type 从注册表查找并渲染对应 Block，所有组件引用均为模块顶层静态声明，
+ * 满足 react-hooks/static-components 规则。
+ * 新增 Block 类型时，在此 switch 中添加对应 case 即可。
+ */
+export function BlockRenderer(props: BlockRenderProps & { type: BlockType }): ReactElement | null {
+  const { type, ...rest } = props;
+  switch (type) {
+    case "exercise":
+      return (
+        <ExerciseBlock
+          blockId={rest.blockId}
+          data={rest.data as ExerciseBlockData}
+          classes={rest.classes ?? []}
+          textbookId={rest.textbookId}
+          chapterId={rest.chapterId}
+        />
+      );
+    case "text_study":
+      return <TextStudyBlock blockId={rest.blockId} data={rest.data as TextStudyBlockData} />;
+    case "reflection":
+      return <ReflectionBlock data={rest.data as RichTextBlockData} onUpdate={rest.onUpdate} />;
+    case "objective":
+    case "key_point":
+    case "import":
+    case "new_teaching":
+    case "consolidation":
+    case "summary":
+    case "homework":
+    case "blackboard":
+    case "rich_text":
+      return (
+        <RichTextBlock
+          data={rest.data as RichTextBlockData}
+          textbookId={rest.textbookId}
+          chapterId={rest.chapterId}
+          onUpdate={rest.onUpdate}
+        />
+      );
+    default:
+      return null;
+  }
+}