refactor(attendance,elective): 审计第二轮 — 全量完成 P0/P1 改进项

P0 修复：
- 页面层 i18n 全量补齐（admin/teacher/parent/student × attendance/elective）
- types.ts 状态标签常量迁移至 constants.ts（i18n key + Badge variant）
- 修复 getTranslations 导入路径（next-intl → next-intl/server）

P1 改进：
- 解耦 parent 模块对 attendance 类型的直接依赖（本地 view-model 类型）
- 导出纯函数（computeStats/buildWarnings/buildLotteryRankCase 等）
- 统一空状态为 EmptyState 组件
- 清理死代码读 Action（attendance 5 个 + elective 3 个）
- 预留监控埋点接口（trackEvent 13 个新事件名）
- 补齐骨架屏 loading.tsx（8 个页面）
- AlertDialog 替换 window.confirm（student-selection-view）
- a11y 改进（aria-label/role/键盘导航）

修复：
- AttendanceStatus 从 constants.ts 重导出，消除 types/constants 双源混乱
- buildWarnings 的 Translator 类型改用 ReturnType<typeof useTranslations>

src/app/(dashboard)/admin/elective/[id]/edit/loading.tsx

@@ -0,0 +1,27 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="flex h-full flex-col space-y-8 p-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <Card>
+        <CardHeader>
+          <Skeleton className="h-5 w-32" />
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <div key={i} className="space-y-2">
+              <Skeleton className="h-4 w-24" />
+              <Skeleton className="h-9 w-full" />
+            </div>
+          ))}
+          <Skeleton className="h-10 w-32" />
+        </CardContent>
+      </Card>
+    </div>
+  )
+}

src/app/(dashboard)/admin/elective/[id]/edit/page.tsx

@@ -1,16 +1,11 @@
 import { notFound } from "next/navigation"
-import type { Metadata } from "next"
 import type { JSX } from "react"
+import { getTranslations } from "next-intl/server"
 
 import { getElectiveCourseById } from "@/modules/elective/data-access"
 import { getGrades, getStaffOptions, getSubjectOptions } from "@/modules/school/data-access"
 import { ElectiveCourseForm } from "@/modules/elective/components/elective-course-form"
 
-export const metadata: Metadata = {
-  title: "编辑选修课程 - Next_Edu",
-  description: "更新选修课程详情",
-}
-
 export const dynamic = "force-dynamic"
 
 export default async function EditElectiveCoursePage({
@@ -18,6 +13,7 @@ export default async function EditElectiveCoursePage({
 }: {
   params: Promise<{ id: string }>
 }): Promise<JSX.Element> {
+  const t = await getTranslations("elective")
   const { id } = await params
 
   const [course, subjects, grades, teachers] = await Promise.all([
@@ -32,15 +28,15 @@ export default async function EditElectiveCoursePage({
   return (
     <div className="flex h-full flex-col space-y-8 p-8">
       <div>
-        <h2 className="text-2xl font-bold tracking-tight">编辑选修课程</h2>
-        <p className="text-muted-foreground">更新选修课程详情。</p>
+        <h2 className="text-2xl font-bold tracking-tight">{t("title.edit")}</h2>
+        <p className="text-muted-foreground">{t("description.edit")}</p>
       </div>
       <ElectiveCourseForm
         mode="edit"
         course={course}
         subjects={subjects}
         grades={grades.map((g) => ({ id: g.id, name: g.name }))}
-        teachers={teachers.map((t) => ({ id: t.id, name: t.name }))}
+        teachers={teachers.map((teacher) => ({ id: teacher.id, name: teacher.name }))}
         backHref="/admin/elective"
       />
     </div>

src/app/(dashboard)/admin/elective/create/loading.tsx

@@ -0,0 +1,27 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="flex h-full flex-col space-y-8 p-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-64" />
+      </div>
+      <Card>
+        <CardHeader>
+          <Skeleton className="h-5 w-32" />
+        </CardHeader>
+        <CardContent className="space-y-4">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <div key={i} className="space-y-2">
+              <Skeleton className="h-4 w-24" />
+              <Skeleton className="h-9 w-full" />
+            </div>
+          ))}
+          <Skeleton className="h-10 w-32" />
+        </CardContent>
+      </Card>
+    </div>
+  )
+}

src/app/(dashboard)/admin/elective/create/page.tsx

@@ -1,17 +1,13 @@
-import type { Metadata } from "next"
 import type { JSX } from "react"
+import { getTranslations } from "next-intl/server"
 
 import { getGrades, getStaffOptions, getSubjectOptions } from "@/modules/school/data-access"
 import { ElectiveCourseForm } from "@/modules/elective/components/elective-course-form"
 
-export const metadata: Metadata = {
-  title: "新建选修课程 - Next_Edu",
-  description: "创建新的选修课程",
-}
-
 export const dynamic = "force-dynamic"
 
 export default async function CreateElectiveCoursePage(): Promise<JSX.Element> {
+  const t = await getTranslations("elective")
   const [subjects, grades, teachers] = await Promise.all([
     getSubjectOptions(),
     getGrades(),
@@ -21,14 +17,14 @@ export default async function CreateElectiveCoursePage(): Promise<JSX.Element> {
   return (
     <div className="flex h-full flex-col space-y-8 p-8">
       <div>
-        <h2 className="text-2xl font-bold tracking-tight">新建选修课程</h2>
-        <p className="text-muted-foreground">创建新的选修课程。</p>
+        <h2 className="text-2xl font-bold tracking-tight">{t("title.create")}</h2>
+        <p className="text-muted-foreground">{t("description.create")}</p>
       </div>
       <ElectiveCourseForm
         mode="create"
         subjects={subjects}
         grades={grades.map((g) => ({ id: g.id, name: g.name }))}
-        teachers={teachers.map((t) => ({ id: t.id, name: t.name }))}
+        teachers={teachers.map((teacher) => ({ id: teacher.id, name: teacher.name }))}
         backHref="/admin/elective"
       />
     </div>

src/app/(dashboard)/admin/elective/loading.tsx

@@ -0,0 +1,27 @@
+import { Card, CardContent, CardHeader } from "@/shared/components/ui/card"
+import { Skeleton } from "@/shared/components/ui/skeleton"
+
+export default function Loading() {
+  return (
+    <div className="space-y-8 p-8">
+      <div className="space-y-2">
+        <Skeleton className="h-8 w-48" />
+        <Skeleton className="h-4 w-72" />
+      </div>
+      <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
+        {Array.from({ length: 6 }).map((_, i) => (
+          <Card key={i}>
+            <CardHeader>
+              <Skeleton className="h-5 w-32" />
+            </CardHeader>
+            <CardContent className="space-y-2">
+              <Skeleton className="h-4 w-full" />
+              <Skeleton className="h-4 w-3/4" />
+              <Skeleton className="h-8 w-24" />
+            </CardContent>
+          </Card>
+        ))}
+      </div>
+    </div>
+  )
+}

src/app/(dashboard)/admin/elective/page.tsx

@@ -1,16 +1,12 @@
-import type { Metadata } from "next"
+import type { Metadata } from "next"
 import type { JSX } from "react"
+import { getTranslations } from "next-intl/server"
 
 import { getElectiveCourses } from "@/modules/elective/data-access"
 import { ElectiveCourseList } from "@/modules/elective/components/elective-course-list"
 import { getSearchParam, type SearchParams } from "@/shared/lib/utils"
 import type { ElectiveCourseStatus } from "@/modules/elective/types"
 
-export const metadata: Metadata = {
-  title: "选修课程 - Next_Edu",
-  description: "管理选修课程、开放/关闭选课与抽签",
-}
-
 export const dynamic = "force-dynamic"
 
 const isValidStatus = (v?: string): v is ElectiveCourseStatus =>
@@ -22,6 +18,7 @@ export default async function AdminElectivePage({
   searchParams: Promise<SearchParams>
 }): Promise<JSX.Element> {
   const sp = await searchParams
+  const t = await getTranslations("elective")
   const statusParam = getSearchParam(sp, "status")
   const status = isValidStatus(statusParam) ? statusParam : undefined
 
@@ -30,9 +27,9 @@ export default async function AdminElectivePage({
   return (
     <div className="flex h-full flex-col space-y-8 p-8">
       <div className="space-y-1">
-        <h2 className="text-2xl font-bold tracking-tight">选修课程</h2>
+        <h2 className="text-2xl font-bold tracking-tight">{t("title.adminList")}</h2>
         <p className="text-muted-foreground">
-          管理选修课程、开放/关闭选课与抽签。
+          {t("description.adminList")}
         </p>
       </div>
       <ElectiveCourseList