feat(attendance,elective): 考勤与选修课模块审计重构 — P0 修复 + i18n + Error Boundary

审计报告：docs/architecture/audit/attendance-elective-audit-report.md

P0 修复：
- attendance: getAttendanceStats 统计失真（仅基于前 20 条记录）改为 SQL 聚合查询
- attendance: getClassStudentsForAttendance 跨模块直查 classEnrollments 改为调用 classes data-access
- attendance: update/delete Action 新增资源归属校验（assertRecordOwnership）
- elective: update/delete/openSelection/closeSelection/runLottery Action 新增资源归属校验（assertCourseOwnership）

i18n 接入：
- 新增 attendance/elective 命名空间（zh-CN + en）
- attendance-stats-cards 接入 useTranslations
- elective-course-list/form 接入 useTranslations

类型安全（P1）：
- elective-course-form: 移除 as 断言，改用类型守卫 isSelectionMode
- elective-course-list: 移除 null as never 类型逃逸，改用泛型

Error Boundary：
- 新增 admin/teacher attendance error.tsx
- 新增 admin/student elective error.tsx

架构图同步：
- 004: 修正 attendance/elective/parent 章节的导出函数、文件清单、已知问题
- 005: 修正 actions 的 usedBy（标记无调用方的死代码）、新增 issues 字段、更新依赖矩阵

src/modules/elective/components/elective-course-form.tsx

@@ -2,6 +2,7 @@
 
 import { useState } from "react"
 import { useRouter } from "next/navigation"
+import { useTranslations } from "next-intl"
 import { toast } from "sonner"
 
 import { Button } from "@/shared/components/ui/button"
@@ -18,7 +19,7 @@ import {
 } from "@/shared/components/ui/select"
 
 import { createElectiveCourseAction, updateElectiveCourseAction } from "../actions"
-import type { ElectiveCourseWithDetails } from "../types"
+import type { ElectiveCourseWithDetails, ElectiveSelectionMode } from "../types"
 
 type Mode = "create" | "edit"
 
@@ -27,6 +28,9 @@ interface Option {
   name: string
 }
 
+const isSelectionMode = (v: string): v is ElectiveSelectionMode =>
+  v === "fcfs" || v === "lottery"
+
 export function ElectiveCourseForm({
   mode,
   course,
@@ -43,12 +47,13 @@ export function ElectiveCourseForm({
   backHref?: string
 }) {
   const router = useRouter()
+  const t = useTranslations("elective")
   const [isWorking, setIsWorking] = useState(false)
 
   const [subjectId, setSubjectId] = useState(course?.subjectId ?? "")
   const [gradeId, setGradeId] = useState(course?.gradeId ?? "")
   const [teacherId, setTeacherId] = useState(course?.teacherId ?? "")
-  const [selectionMode, setSelectionMode] = useState(course?.selectionMode ?? "fcfs")
+  const [selectionMode, setSelectionMode] = useState<ElectiveSelectionMode>(course?.selectionMode ?? "fcfs")
 
   const handleSubmit = async (formData: FormData) => {
     setIsWorking(true)
@@ -200,14 +205,19 @@ export function ElectiveCourseForm({
             </div>
 
             <div className="grid gap-2">
-              <Label>Selection Mode</Label>
-              <Select value={selectionMode} onValueChange={(v) => setSelectionMode(v as "fcfs" | "lottery")}>
+              <Label>{t("fields.selectionMode")}</Label>
+              <Select
+                value={selectionMode}
+                onValueChange={(v) => {
+                  if (isSelectionMode(v)) setSelectionMode(v)
+                }}
+              >
                 <SelectTrigger>
                   <SelectValue />
                 </SelectTrigger>
                 <SelectContent>
-                  <SelectItem value="fcfs">First Come First Served</SelectItem>
-                  <SelectItem value="lottery">Lottery</SelectItem>
+                  <SelectItem value="fcfs">{t("selectionMode.fcfs")}</SelectItem>
+                  <SelectItem value="lottery">{t("selectionMode.lottery")}</SelectItem>
                 </SelectContent>
               </Select>
               <input type="hidden" name="selectionMode" value={selectionMode} />

src/modules/elective/components/elective-course-list.tsx

@@ -2,6 +2,7 @@
 
 import { useState, useTransition } from "react"
 import { useRouter } from "next/navigation"
+import { useTranslations } from "next-intl"
 import { toast } from "sonner"
 import { Plus, Pencil, Lock, Unlock, Shuffle, Trash2 } from "lucide-react"
 
@@ -10,6 +11,7 @@ import { Button } from "@/shared/components/ui/button"
 import { Card, CardContent, CardHeader, CardTitle } from "@/shared/components/ui/card"
 import { EmptyState } from "@/shared/components/ui/empty-state"
 import { usePermission } from "@/shared/hooks/use-permission"
+import type { ActionState } from "@/shared/types/action-state"
 import { Permissions } from "@/shared/types/permissions"
 
 import {
@@ -37,13 +39,14 @@ export function ElectiveCourseList({
   canManage?: boolean
 }) {
   const router = useRouter()
+  const t = useTranslations("elective")
   const { hasPermission } = usePermission()
   const manageResolved = canManage ?? hasPermission(Permissions.ELECTIVE_MANAGE)
   const [pendingId, setPendingId] = useState<string | null>(null)
   const [isPending, startTransition] = useTransition()
 
-  const runAction = async (
-    action: (prevState: never, formData: FormData) => Promise<{ success: boolean; message?: string }>,
+  const runAction = async <T,>(
+    action: (prevState: ActionState<T> | null, formData: FormData) => Promise<ActionState<T>>,
     courseId: string,
     successMsg: string
   ) => {
@@ -51,7 +54,7 @@ export function ElectiveCourseList({
     startTransition(async () => {
       const formData = new FormData()
       formData.set("courseId", courseId)
-      const res = await action(null as never, formData)
+      const res = await action(null, formData)
       if (res.success) {
         toast.success(res.message ?? successMsg)
         router.refresh()
@@ -82,13 +85,13 @@ export function ElectiveCourseList({
     <div className="space-y-6">
       <div className="flex flex-wrap items-center justify-between gap-3">
         <p className="text-sm text-muted-foreground">
-          {courses.length} course{courses.length === 1 ? "" : "s"}
+          {courses.length} {t("title.adminList")}
         </p>
         {manageResolved && createHref ? (
           <Button asChild>
             <a href={createHref}>
               <Plus className="mr-2 h-4 w-4" />
-              New Course
+              {t("actions.create")}
             </a>
           </Button>
         ) : null}
@@ -96,8 +99,8 @@ export function ElectiveCourseList({
 
       {courses.length === 0 ? (
         <EmptyState
-          title="No elective courses"
-          description="There are no elective courses available."
+          title={t("list.empty")}
+          description={t("list.emptyDescription")}
           icon={Plus}
           className="h-auto border-none shadow-none"
         />