feat(textbooks): 教材模块审计重构 — 跨模块解耦 + 权限 + i18n + 错误边界 + 纯函数抽取

P0 修复：
- 解耦跨模块 UI 依赖：knowledge-point-dialogs 不再直接 import questions，
  改为 renderQuestionCreator render prop 由页面注入
- 接入 usePermission Hook 替换 canEdit 硬编码
- 全模块 i18n 改造：新增 en/zh-CN 翻译文件，替换所有硬编码文案
- Server Action 资源归属校验：新增 verifyChapterBelongsToTextbook/
  verifyKnowledgePointBelongsToTextbook，在 reorder/update/delete/create 中校验

P1 改进：
- 补齐 Error Boundary：4 个 error.tsx + TextbookSectionErrorBoundary 区块包裹
- 抽取纯函数到 utils.ts/graph-layout.ts/constants.ts 并补单测（26 用例全通过）
- 消除重复组件：删除 knowledge-point-panel/create-knowledge-point-dialog
- 修复类型断言：chapter.children! → 守卫式访问
- 图谱 a11y：添加 role/aria-label/aria-pressed
- 统一删除确认：confirm() → AlertDialog
- 数据范围过滤：getTextbooksWithScope 支持学生端按年级过滤

P2 预留：
- TextbookAnalytics 埋点接口 + Provider + Hook

同步 005 架构数据 JSON：补充 getTextbooksWithScope/verify*/ChapterTreeNode 等

src/modules/textbooks/components/knowledge-point-list.tsx

@@ -1,6 +1,7 @@
 "use client"
 
 import { PlusCircle, Pencil, Trash2 } from "lucide-react"
+import { useTranslations } from "next-intl"
 
 import type { KnowledgePoint } from "../types"
 import { cn } from "@/shared/lib/utils"
@@ -11,6 +12,8 @@ import { Button } from "@/shared/components/ui/button"
 interface KnowledgePointListProps {
   knowledgePoints: KnowledgePoint[]
   canEdit: boolean
+  /** 是否有创建题目权限（控制"创建相关题目"按钮可见性） */
+  canCreateQuestion?: boolean
   highlightedKpId: string | null
   onHighlight: (id: string) => void
   onEdit: (kp: KnowledgePoint) => void
@@ -21,16 +24,19 @@ interface KnowledgePointListProps {
 export function KnowledgePointList({
   knowledgePoints,
   canEdit,
+  canCreateQuestion = false,
   highlightedKpId,
   onHighlight,
   onEdit,
   onDelete,
   onCreateQuestion,
 }: KnowledgePointListProps) {
+  const t = useTranslations("textbooks")
+
   if (knowledgePoints.length === 0) {
     return (
       <div className="flex h-full items-center justify-center text-muted-foreground p-4 text-center text-sm">
-        该章节暂无知识点。
+        {t("reader.emptyKnowledge")}
       </div>
     )
   }
@@ -51,22 +57,27 @@ export function KnowledgePointList({
             <div className="flex items-start justify-between gap-2">
               <h4 className="text-sm font-medium leading-none">{kp.name}</h4>
               <div className="flex items-center gap-1">
-                <Badge variant="outline" className="text-[10px] h-5 px-1">Lv.{kp.level}</Badge>
+                <Badge variant="outline" className="text-[10px] h-5 px-1">
+                  {t("panel.level")}
+                  {kp.level}
+                </Badge>
                 {canEdit && (
                   <div className="flex items-center gap-1 ml-1">
-                    <Button
-                      variant="ghost"
-                      size="icon"
-                      className="h-5 w-5 text-muted-foreground hover:text-foreground"
-                      onClick={(e) => {
-                        e.stopPropagation()
-                        onCreateQuestion(kp)
-                      }}
-                      title="创建相关题目"
-                      aria-label="创建相关题目"
-                    >
-                      <PlusCircle className="h-3 w-3" />
-                    </Button>
+                    {canCreateQuestion && (
+                      <Button
+                        variant="ghost"
+                        size="icon"
+                        className="h-5 w-5 text-muted-foreground hover:text-foreground"
+                        onClick={(e) => {
+                          e.stopPropagation()
+                          onCreateQuestion(kp)
+                        }}
+                        title={t("dialog.knowledge.createQuestion")}
+                        aria-label={t("dialog.knowledge.createQuestion")}
+                      >
+                        <PlusCircle className="h-3 w-3" />
+                      </Button>
+                    )}
                     <Button
                       variant="ghost"
                       size="icon"
@@ -75,8 +86,8 @@ export function KnowledgePointList({
                         e.stopPropagation()
                         onEdit(kp)
                       }}
-                      title="编辑知识点"
-                      aria-label="编辑知识点"
+                      title={t("dialog.knowledge.editKp")}
+                      aria-label={t("dialog.knowledge.editKp")}
                     >
                       <Pencil className="h-3 w-3" />
                     </Button>
@@ -85,8 +96,8 @@ export function KnowledgePointList({
                       size="icon"
                       className="h-5 w-5 text-muted-foreground hover:text-destructive"
                       onClick={(e) => onDelete(kp.id, e)}
-                      title="删除知识点"
-                      aria-label="删除知识点"
+                      title={t("dialog.knowledge.deleteKp")}
+                      aria-label={t("dialog.knowledge.deleteKp")}
                     >
                       <Trash2 className="h-3 w-3" />
                     </Button>