feat(textbooks): 知识图谱功能全面重构 — 前置依赖 + dagre 布局 + React Flow 可视化 + 师生双视角

将教材模块图谱从基本无用状态升级为完整知识图谱可视化系统。

数据层：新增 knowledgePointPrerequisites 表（复合主键+双外键 cascade）；新增 data-access-graph.ts（server-only）知识点关联聚合、学生/班级掌握度查询；utils.ts 新增 hasCycleAfterAddingEdge（DFS 循环依赖检测）。

业务层：3 个新 Server Action（getKnowledgeGraphDataAction 三视图模式、createPrerequisiteAction 含循环检测、deletePrerequisiteAction）；graph-layout.ts 重写为 dagre 分层有向图布局。

视图层：knowledge-graph.tsx 重写为 React Flow 主组件（全书视图+搜索高亮+关联节点高亮+章节着色）；4 个新组件（graph-kp-node/graph-prerequisite-edge/graph-toolbar/graph-node-detail-panel）；use-graph-data.ts 派生值模式避免 effect 中 setState。

架构：严格三层架构，客户端通过 Server Action 间接访问 server-only 数据层；权限校验+ i18n 全覆盖；架构文档 004/005 同步。

测试：utils.test.ts 新增 5 个循环检测测试，graph-layout.test.ts 重写 5 个 dagre 布局测试，全部 30 个教材模块单元测试通过。

附带提交 drizzle/0005 error-book 迁移文件以保持 journal 一致性。

src/shared/i18n/messages/zh-CN/textbooks.json

@@ -34,10 +34,16 @@
       "graph": "图谱"
     },
     "selectChapter": "请选择一个章节开始阅读。",
+    "selectChapterDesc": "从左侧目录中选择一个章节以查看内容。",
     "selectChapterKnowledge": "请选择一个章节查看知识点。",
+    "selectChapterKnowledgeDesc": "从左侧目录中选择一个章节以查看关联的知识点。",
     "selectChapterGraph": "请选择一个章节查看知识图谱。",
+    "selectChapterGraphDesc": "从左侧目录中选择一个章节以查看知识图谱关系。",
     "emptyKnowledge": "该章节暂无知识点。",
+    "emptyKnowledgeDesc": "在阅读内容时选中文本即可创建知识点。",
     "emptyContent": "暂无内容",
+    "emptyContentDesc": "点击「编辑内容」开始编写本章正文。",
+    "loadingKnowledge": "正在加载知识点...",
     "editContent": "编辑内容",
     "cancel": "取消",
     "save": "保存",
@@ -45,7 +51,9 @@
     "addKnowledgePoint": "添加知识点",
     "clickToViewKp": "点击查看知识点详情",
     "noChapters": "暂无章节",
-    "noChaptersDesc": "这本教材还没有章节。"
+    "noChaptersDesc": "这本教材还没有章节。",
+    "sidebar": "目录与知识点",
+    "openSidebar": "打开目录"
   },
   "dialog": {
     "create": {
@@ -75,7 +83,11 @@
       "deleting": "删除中...",
       "cannotDeleteWithSubchapters": "无法删除含有子章节的章节",
       "addSubchapter": "添加子章节",
-      "titlePlaceholder": "例如：第一章：入门"
+      "titlePlaceholder": "例如：第一章：入门",
+      "toggle": "展开/折叠",
+      "orderUpdated": "顺序已更新",
+      "cancel": "取消",
+      "dragHandle": "拖拽排序"
     },
     "knowledge": {
       "createTitle": "添加知识点",
@@ -133,6 +145,7 @@
     "level": "等级"
   },
   "subject": {
+    "chinese": "语文",
     "mathematics": "数学",
     "physics": "物理",
     "chemistry": "化学",
@@ -142,6 +155,8 @@
     "geography": "地理"
   },
   "grade": {
+    "grade1": "一年级",
+    "grade2": "二年级",
     "grade7": "七年级",
     "grade8": "八年级",
     "grade9": "九年级",
@@ -160,7 +175,7 @@
     "updateSuccess": "教材更新成功。",
     "updateFailed": "更新教材失败。",
     "deleteSuccess": "教材删除成功。",
-    "deleteFailed": "删除教材失败。",
+    "textbookDeleteFailed": "删除教材失败。",
     "chapterCreateSuccess": "章节创建成功",
     "chapterCreateFailed": "创建章节失败",
     "chapterDeleteSuccess": "章节删除成功",
@@ -181,6 +196,57 @@
     "invalidContent": "章节内容数据无效",
     "errorOccurred": "发生错误",
     "deleteFailed": "删除失败",
-    "updateFailedGeneric": "更新失败"
+    "updateFailedGeneric": "更新失败",
+    "chapterNotBelong": "章节不属于该教材",
+    "kpNotBelong": "知识点不属于该教材",
+    "chaptersReordered": "章节排序成功",
+    "ok": "成功",
+    "kpLoadFailed": "加载知识点失败",
+    "graphLoadFailed": "图谱加载失败",
+    "invalidInput": "输入无效",
+    "cyclicDependency": "不能添加循环依赖",
+    "prerequisiteCreated": "前置依赖已添加",
+    "prerequisiteCreateFailed": "添加前置依赖失败",
+    "prerequisiteDeleted": "前置依赖已删除",
+    "prerequisiteDeleteFailed": "删除前置依赖失败"
+  },
+  "graph": {
+    "viewMode": {
+      "structure": "结构图",
+      "studentMastery": "个人掌握度",
+      "classMastery": "班级掌握度"
+    },
+    "node": {
+      "questions": "题目",
+      "mastery": "掌握度",
+      "prerequisite": "前置",
+      "successor": "后置"
+    },
+    "detail": {
+      "title": "知识点详情",
+      "noDescription": "暂无描述",
+      "viewAllQuestions": "查看全部题目",
+      "editPrerequisite": "编辑前置依赖",
+      "addPrerequisite": "添加前置",
+      "removePrerequisite": "移除",
+      "noPrerequisites": "暂无前置知识点",
+      "noSuccessors": "暂无后置知识点",
+      "masteryNotAssessed": "未测评",
+      "correctRate": "正确率",
+      "totalQuestions": "总题数"
+    },
+    "toolbar": {
+      "search": "搜索知识点",
+      "filterByChapter": "按章节筛选",
+      "resetView": "重置视图"
+    },
+    "empty": {
+      "noPrerequisites": "暂无前置依赖关系",
+      "noData": "暂无图谱数据"
+    },
+    "error": {
+      "cyclicDependency": "不能添加循环依赖",
+      "loadFailed": "图谱加载失败"
+    }
   }
 }