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/app/(dashboard)/teacher/textbooks/page.tsx

@@ -1,6 +1,7 @@
 import type { JSX } from "react"
 import { Suspense } from "react"
 import { BookOpen } from "lucide-react"
+import { getTranslations } from "next-intl/server"
 import { TextbookCard } from "@/modules/textbooks/components/textbook-card"
 import { TextbookFormDialog } from "@/modules/textbooks/components/textbook-form-dialog"
 import { getTextbooks } from "@/modules/textbooks/data-access"
@@ -10,7 +11,13 @@ import { getParam, type SearchParams } from "@/shared/lib/search-params"
 
 export const dynamic = "force-dynamic"
 
-async function TextbooksResults({ searchParams }: { searchParams: Promise<SearchParams> }): Promise<JSX.Element> {
+async function TextbooksResults({
+  searchParams,
+  t,
+}: {
+  searchParams: Promise<SearchParams>
+  t: Awaited<ReturnType<typeof getTranslations<"textbooks">>>
+}): Promise<JSX.Element> {
   const params = await searchParams
 
   const q = getParam(params, "q") || undefined
@@ -25,9 +32,17 @@ async function TextbooksResults({ searchParams }: { searchParams: Promise<Search
     return (
       <EmptyState
         icon={BookOpen}
-        title={hasFilters ? "No textbooks match your filters" : "No textbooks yet"}
-        description={hasFilters ? "Try clearing filters or adjusting keywords." : "Create your first textbook to start organizing chapters."}
-        action={hasFilters ? { label: "Clear filters", href: "/teacher/textbooks" } : undefined}
+        title={hasFilters ? t("list.empty.withFilters") : t("list.empty.withoutFilters")}
+        description={
+          hasFilters
+            ? t("list.empty.withFiltersDesc")
+            : t("list.empty.withoutFiltersDesc")
+        }
+        action={
+          hasFilters
+            ? { label: t("list.clearFilters"), href: "/teacher/textbooks" }
+            : undefined
+        }
         className="min-h-[400px] border-muted-foreground/10"
       />
     )
@@ -42,16 +57,20 @@ async function TextbooksResults({ searchParams }: { searchParams: Promise<Search
   )
 }
 
-export default async function TextbooksPage({ searchParams }: { searchParams: Promise<SearchParams> }): Promise<JSX.Element> {
+export default async function TextbooksPage({
+  searchParams,
+}: {
+  searchParams: Promise<SearchParams>
+}): Promise<JSX.Element> {
+  const t = await getTranslations("textbooks")
+
   return (
     <div className="space-y-6 p-8">
       {/* Page Header */}
       <div className="flex flex-col gap-4 md:flex-row md:items-center md:justify-between">
         <div>
-          <h1 className="text-2xl font-bold tracking-tight">Textbooks</h1>
-          <p className="text-muted-foreground">
-            Manage your digital curriculum resources and chapters.
-          </p>
+          <h1 className="text-2xl font-bold tracking-tight">{t("list.title")}</h1>
+          <p className="text-muted-foreground">{t("list.subtitle")}</p>
         </div>
         <TextbookFormDialog />
       </div>
@@ -61,7 +80,7 @@ export default async function TextbooksPage({ searchParams }: { searchParams: Pr
       </Suspense>
 
       <Suspense fallback={<div className="h-[360px] w-full animate-pulse rounded-md bg-muted" />}>
-        <TextbooksResults searchParams={searchParams} />
+        <TextbooksResults searchParams={searchParams} t={t} />
       </Suspense>
     </div>
   )