feat: 从书籍生成教案（粘贴目录 + 上传 md 压缩包）

新增「从书籍生成」流程：用户粘贴教材目录（多行）并上传内含各章
.md 的 ZIP（文件名=目录标题），前端用 JSZip 解压匹配，AI 按章节
体量划分课时，预览/编辑后批量生成，每篇以对应章节正文作为上下文。

服务端
- generate.ts: 新增 POST /lessons-from-book（目录条目→AI 划分课时
  JSON，剥围栏/校验/丢非法行）；扩展 POST / 支持可选 content 上下文，
  无 content 时请求体不变（向后兼容）。

前端
- bookImport.ts: normalizeTitle / parseZip / matchToc / assembleContent。
- booksApi.ts: generateLesson 兼容签名 + divideLessonsFromBook。
- useTeachingBook.ts: 抽出 runGenerationPool，新增 generateLessonsFromBook。
- BookImportDialog.vue 多阶段对话框；UploadDropzone 加 accept/multiple；
  菜单串接「从书籍生成」。

顺带修复 5 个遗留失败测试：import 功能已于 fb0b8d1 删除但测试漏删，
清理孤儿测试；批量生成对齐为单参 generateLesson(topic)。

docs/book-import-spec.md 记录规格。

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/components/WorkspaceView.vue

@@ -1,10 +1,11 @@
 <script setup lang="ts">
 import { ref } from 'vue'
-import { useTeachingBook } from '../composables/useTeachingBook'
+import { useTeachingBook, type BookLessonInput } from '../composables/useTeachingBook'
 import type { TeachingDesign } from '../../shared/domain/teachingDesign'
 import { createBookZip, downloadBlob } from '../services/zipExporter'
 import A4Workspace from './A4Workspace.vue'
 import BatchGenerateDialog from './BatchGenerateDialog.vue'
+import BookImportDialog from './BookImportDialog.vue'
 import FixBrokenDialog from './FixBrokenDialog.vue'
 import GenerateLessonDialog from './GenerateLessonDialog.vue'
 import LessonSidebar from './LessonSidebar.vue'
@@ -35,6 +36,7 @@ const {
   clearBook,
   generateLesson,
   generateLessons,
+  generateLessonsFromBook,
   regenerateLesson,
 } = useTeachingBook(props.bookId)
 
@@ -52,6 +54,14 @@ const batchCurrentTopic = ref('')
 const batchError = ref<string | null>(null)
 const batchCancelled = ref(false)
 
+const showBookImportDialog = ref(false)
+const bookImportRunning = ref(false)
+const bookImportDone = ref(0)
+const bookImportTotal = ref(0)
+const bookImportCurrentTopic = ref('')
+const bookImportError = ref<string | null>(null)
+const bookImportCancelled = ref(false)
+
 const showFixDialog = ref(false)
 const fixRunning = ref(false)
 const fixDone = ref(0)
@@ -153,6 +163,42 @@ function closeBatchDialog(): void {
   batchError.value = null
 }
 
+async function handleBookImportStart(lessons: BookLessonInput[]): Promise<void> {
+  bookImportRunning.value = true
+  bookImportCancelled.value = false
+  bookImportDone.value = 0
+  bookImportTotal.value = lessons.length
+  bookImportError.value = null
+
+  const result = await generateLessonsFromBook(lessons, {
+    concurrency: BATCH_GENERATE_CONCURRENCY,
+    isCancelled: () => bookImportCancelled.value,
+    onTopicStart: (topic) => {
+      bookImportCurrentTopic.value = topic
+    },
+    onLessonComplete: (count) => {
+      bookImportDone.value += count
+    },
+  })
+
+  if (!result.ok) {
+    bookImportError.value = result.message
+  }
+
+  bookImportRunning.value = false
+}
+
+function handleBookImportCancel(): void {
+  bookImportCancelled.value = true
+}
+
+function closeBookImportDialog(): void {
+  showBookImportDialog.value = false
+  bookImportDone.value = 0
+  bookImportTotal.value = 0
+  bookImportError.value = null
+}
+
 function openFixDialog(): void {
   fixTotal.value = book.value.designs.filter((d) => d.warnings.length > 0).length
   fixDone.value = 0
@@ -220,6 +266,17 @@ function closeFixDialog(): void {
         @cancel="handleBatchCancel"
         @close="closeBatchDialog"
       />
+      <BookImportDialog
+        v-if="showBookImportDialog"
+        :running="bookImportRunning"
+        :done="bookImportDone"
+        :total="bookImportTotal"
+        :current-topic="bookImportCurrentTopic"
+        :error="bookImportError"
+        @start="handleBookImportStart"
+        @cancel="handleBookImportCancel"
+        @close="closeBookImportDialog"
+      />
       <FixBrokenDialog
         v-if="showFixDialog"
         :running="fixRunning"
@@ -247,6 +304,7 @@ function closeFixDialog(): void {
         @back="$emit('back')"
         @generate="openGenerateDialog"
         @batch-generate="showBatchDialog = true"
+        @book-import="showBookImportDialog = true"
         @fix-broken="openFixDialog"
         @print="handlePrint"
         @export="handleExport"