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

@@ -0,0 +1,155 @@
+"use client";
+
+import { useState } from "react";
+import { useLessonPlanEditor } from "../../hooks/use-lesson-plan-editor";
+import { QuestionBankPicker } from "../question-bank-picker";
+import { InlineQuestionEditor } from "../inline-question-editor";
+import { PublishHomeworkDialog } from "../publish-homework-dialog";
+import { Button } from "@/shared/components/ui/button";
+import { Plus, Trash2 } from "lucide-react";
+import type {
+  ExerciseBlockData,
+  ExerciseItem,
+} from "../../types";
+
+interface Props {
+  blockId: string;
+  data: ExerciseBlockData;
+  classes: { id: string; name: string }[];
+}
+
+export function ExerciseBlock({ blockId, data, classes }: Props) {
+  const { updateNode, planId } = useLessonPlanEditor();
+  const [showBank, setShowBank] = useState(false);
+  const [showInline, setShowInline] = useState(false);
+  const [showPublish, setShowPublish] = useState(false);
+
+  function update(patch: Partial<ExerciseBlockData>) {
+    updateNode(blockId, { data: { ...data, ...patch } });
+  }
+
+  function addItems(items: ExerciseItem[]) {
+    const next = [...data.items, ...items];
+    update({
+      items: next.map((it, i) => ({ ...it, order: i })),
+    });
+  }
+
+  function removeItem(idx: number) {
+    update({
+      items: data.items
+        .filter((_, i) => i !== idx)
+        .map((it, i) => ({ ...it, order: i })),
+    });
+  }
+
+  return (
+    <div className="space-y-2">
+      <div className="flex gap-2">
+        <select
+          value={data.purpose}
+          onChange={(e) =>
+            update({ purpose: e.target.value as never })
+          }
+          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>
+        </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
+        </p>
+      ) : (
+        <div className="space-y-1">
+          {data.items.map((item, idx) => (
+            <div
+              key={idx}
+              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"}
+              </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"}
+              </span>
+              <span className="text-xs">{item.score}分</span>
+              <button onClick={() => removeItem(idx)}>
+                <Trash2 className="w-3 h-3 text-error" />
+              </button>
+            </div>
+          ))}
+        </div>
+      )}
+      <div className="flex gap-2 flex-wrap">
+        <Button
+          variant="outline"
+          size="sm"
+          onClick={() => setShowBank(true)}
+        >
+          <Plus className="w-3 h-3 mr-1" />
+          从题库添加
+        </Button>
+        <Button
+          variant="outline"
+          size="sm"
+          onClick={() => setShowInline(true)}
+        >
+          <Plus className="w-3 h-3 mr-1" />
+          新建题目
+        </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
+            </span>
+            <a
+              href="/teacher/homework"
+              className="text-primary underline"
+            >
+              查看
+            </a>
+          </div>
+        ) : (
+          data.purpose === "after_class_homework" &&
+          data.items.length > 0 && (
+            <Button
+              size="sm"
+              onClick={() => setShowPublish(true)}
+            >
+              发布为作业
+            </Button>
+          )
+        )}
+      </div>
+      {showBank && (
+        <QuestionBankPicker
+          existingIds={data.items.map((i) => i.questionId)}
+          onPick={addItems}
+          onClose={() => setShowBank(false)}
+        />
+      )}
+      {showInline && (
+        <InlineQuestionEditor
+          onAdd={(item) => {
+            addItems([item]);
+            setShowInline(false);
+          }}
+          onClose={() => setShowInline(false)}
+        />
+      )}
+      {showPublish && (
+        <PublishHomeworkDialog
+          planId={planId}
+          blockId={blockId}
+          classes={classes}
+          onClose={() => setShowPublish(false)}
+          onPublished={() => window.location.reload()}
+        />
+      )}
+    </div>
+  );
+}