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/textbook-form-dialog.tsx

@@ -3,6 +3,7 @@
 import { useState } from "react"
 import { Plus } from "lucide-react"
 import { useFormStatus } from "react-dom"
+import { useTranslations } from "next-intl"
 import { Button } from "@/shared/components/ui/button"
 import {
   Dialog,
@@ -23,22 +24,23 @@ import {
   SelectValue,
 } from "@/shared/components/ui/select"
 import { createTextbookAction } from "../actions"
+import { SUBJECTS, GRADES } from "../constants"
 import { toast } from "sonner"
 
 function SubmitButton() {
   const { pending } = useFormStatus()
+  const t = useTranslations("textbooks")
   return (
     <Button type="submit" disabled={pending}>
-      {pending ? "Saving..." : "Save changes"}
+      {pending ? t("dialog.create.saving") : t("dialog.create.submit")}
     </Button>
   )
 }
 
 export function TextbookFormDialog() {
+  const t = useTranslations("textbooks")
   const [open, setOpen] = useState(false)
 
-  // Using simple form action without useActionState hook for simplicity in this demo environment
-  // In production with React 19/Next 15, we'd use useActionState
   const handleSubmit = async (formData: FormData) => {
     const result = await createTextbookAction(null, formData)
     if (result.success) {
@@ -54,72 +56,70 @@ export function TextbookFormDialog() {
       <DialogTrigger asChild>
         <Button>
           <Plus className="mr-2 h-4 w-4" />
-          Add Textbook
+          {t("list.add")}
         </Button>
       </DialogTrigger>
       <DialogContent className="sm:max-w-[425px]">
         <DialogHeader>
-          <DialogTitle>Add New Textbook</DialogTitle>
-          <DialogDescription>
-            Create a new digital textbook. Click save when you&apos;re done.
-          </DialogDescription>
+          <DialogTitle>{t("dialog.create.title")}</DialogTitle>
+          <DialogDescription>{t("dialog.create.description")}</DialogDescription>
         </DialogHeader>
         <form action={handleSubmit}>
           <div className="grid gap-4 py-4">
             <div className="grid grid-cols-4 items-center gap-4">
               <Label htmlFor="title" className="text-right">
-                Title
+                {t("field.title")}
               </Label>
               <Input
                 id="title"
                 name="title"
-                placeholder="e.g. Advanced Calculus"
+                placeholder={t("field.titlePlaceholder")}
                 className="col-span-3"
                 required
               />
             </div>
             <div className="grid grid-cols-4 items-center gap-4">
               <Label htmlFor="subject" className="text-right">
-                Subject
+                {t("field.subject")}
               </Label>
               <Select name="subject" required>
                 <SelectTrigger className="col-span-3">
-                  <SelectValue placeholder="Select subject" />
+                  <SelectValue placeholder={t("field.subjectPlaceholder")} />
                 </SelectTrigger>
                 <SelectContent>
-                  <SelectItem value="Mathematics">Mathematics</SelectItem>
-                  <SelectItem value="Physics">Physics</SelectItem>
-                  <SelectItem value="Chemistry">Chemistry</SelectItem>
-                  <SelectItem value="Biology">Biology</SelectItem>
-                  <SelectItem value="English">English</SelectItem>
-                  <SelectItem value="History">History</SelectItem>
-                  <SelectItem value="Geography">Geography</SelectItem>
+                  {SUBJECTS.map((s) => (
+                    <SelectItem key={s.value} value={s.value}>
+                      {t(`subject.${s.labelKey}`)}
+                    </SelectItem>
+                  ))}
                 </SelectContent>
               </Select>
             </div>
             <div className="grid grid-cols-4 items-center gap-4">
               <Label htmlFor="grade" className="text-right">
-                Grade
+                {t("field.grade")}
               </Label>
               <Select name="grade" required>
                 <SelectTrigger className="col-span-3">
-                  <SelectValue placeholder="Select grade" />
+                  <SelectValue placeholder={t("field.gradePlaceholder")} />
                 </SelectTrigger>
                 <SelectContent>
-                  <SelectItem value="Grade 10">Grade 10</SelectItem>
-                  <SelectItem value="Grade 11">Grade 11</SelectItem>
-                  <SelectItem value="Grade 12">Grade 12</SelectItem>
+                  {GRADES.map((g) => (
+                    <SelectItem key={g.value} value={g.value}>
+                      {t(`grade.${g.labelKey}`)}
+                    </SelectItem>
+                  ))}
                 </SelectContent>
               </Select>
             </div>
             <div className="grid grid-cols-4 items-center gap-4">
               <Label htmlFor="publisher" className="text-right">
-                Publisher
+                {t("field.publisher")}
               </Label>
               <Input
                 id="publisher"
                 name="publisher"
-                placeholder="e.g. Next Education"
+                placeholder={t("field.publisherPlaceholder")}
                 className="col-span-3"
               />
             </div>