feat(attendance,elective): 实现所有 P2 长期改进项

P2 修复（来自审计报告）：
- 2.4.4: Server Action 错误消息 i18n 化（attendance/elective 全部 Action）
- 2.5.3: 抽取 AttendancePageLayout 组件复用（admin/teacher 页面）
- 2.5.4: 抽取 ElectivePageLayout 组件复用（admin/teacher 列表页）
- 2.6.3: 考勤月历键盘导航（tabIndex + 方向键 + Home/End + role=grid）
- 2.8.2: getStudentAttendanceSummary 分页优化（SQL 聚合统计 + LIMIT 分页）
- 2.8.3: resolveCourseDisplayNames 缓存优化（React cache 去重）
- 2.1.4: elective data-access 跨模块依赖接口抽象（resolvers.ts 可注入）

P2 建议项：
- 选课时间冲突检测（parseSchedule + isScheduleConflict 纯函数 + checkScheduleConflict）
- 学分上限校验（MAX_CREDIT_PER_TERM + checkCreditLimit）
- 考勤/选课数据导出 Excel（export.ts + API 路由扩展）

新增文件：
- src/modules/attendance/components/attendance-page-layout.tsx
- src/modules/elective/components/elective-page-layout.tsx
- src/modules/elective/resolvers.ts
- src/modules/attendance/export.ts
- src/modules/elective/export.ts

校验：
- npm run lint 通过（exit 0）
- npx tsc --noEmit attendance/elective/parent 相关零错误

src/shared/i18n/messages/en/attendance.json

@@ -88,9 +88,21 @@
   "errors": {
     "notFound": "Attendance record not found",
     "noOwnership": "You do not own this attendance record",
+    "noClassOwnership": "You do not own this class",
+    "insufficientPermissions": "Insufficient permissions",
     "invalidForm": "Invalid form data",
+    "missingRecords": "Missing records data",
+    "invalidRecordsJson": "Invalid attendance data format",
     "unexpected": "Unexpected error"
   },
+  "messages": {
+    "recorded": "Attendance recorded",
+    "batchRecorded": "Recorded attendance for {count} students",
+    "updated": "Attendance updated",
+    "deleted": "Attendance record deleted",
+    "rulesSaved": "Attendance rules saved",
+    "ownershipCheckFailed": "Ownership check failed"
+  },
   "parent": {
     "warningTitle": "Attendance Warnings",
     "rateCardTitle": "Attendance Rate Summary",

src/shared/i18n/messages/en/elective.json

@@ -95,7 +95,19 @@
     "alreadySelected": "You have already selected this course",
     "selectionClosed": "Selection is closed",
     "gradeMismatch": "Your grade does not match the course requirement",
+    "scheduleConflict": "Schedule conflicts with your existing courses",
+    "creditExceeded": "Credit limit exceeded ({current}/{max})",
     "invalidForm": "Invalid form data",
     "unexpected": "Unexpected error"
+  },
+  "messages": {
+    "created": "Elective course created",
+    "updated": "Elective course updated",
+    "deleted": "Elective course deleted",
+    "selectionOpened": "Selection opened",
+    "selectionClosed": "Selection closed",
+    "lotteryCompleted": "Lottery completed: {enrolled} enrolled, {waitlist} waitlisted",
+    "courseDropped": "Course dropped",
+    "ownershipCheckFailed": "Ownership check failed"
   }
 }

src/shared/i18n/messages/en/textbooks.json

@@ -58,7 +58,8 @@
     "noChapters": "No chapters",
     "noChaptersDesc": "This textbook has no chapters yet.",
     "sidebar": "Chapters & Knowledge",
-    "openSidebar": "Open Sidebar"
+    "openSidebar": "Open Sidebar",
+    "prepareLesson": "Prepare Lesson for This Text"
   },
   "dialog": {
     "create": {
@@ -91,6 +92,7 @@
       "titlePlaceholder": "e.g. Chapter 1: Introduction",
       "toggle": "Toggle",
       "orderUpdated": "Order updated",
+      "orderUpdateFailed": "Failed to update order",
       "cancel": "Cancel",
       "dragHandle": "Drag to reorder"
     },
@@ -251,7 +253,8 @@
     "toolbar": {
       "search": "Search knowledge points",
       "filterByChapter": "Filter by chapter",
-      "resetView": "Reset view"
+      "resetView": "Reset view",
+      "refreshing": "Refreshing..."
     },
     "empty": {
       "noPrerequisites": "No prerequisite relationships",

src/shared/i18n/messages/zh-CN/attendance.json

@@ -88,9 +88,21 @@
   "errors": {
     "notFound": "考勤记录不存在",
     "noOwnership": "您无权操作此考勤记录",
+    "noClassOwnership": "您无权操作此班级",
+    "insufficientPermissions": "权限不足",
     "invalidForm": "表单数据无效",
+    "missingRecords": "缺少考勤数据",
+    "invalidRecordsJson": "考勤数据格式无效",
     "unexpected": "发生未知错误"
   },
+  "messages": {
+    "recorded": "考勤已记录",
+    "batchRecorded": "已为 {count} 名学生记录考勤",
+    "updated": "考勤已更新",
+    "deleted": "考勤记录已删除",
+    "rulesSaved": "考勤规则已保存",
+    "ownershipCheckFailed": "归属校验失败"
+  },
   "parent": {
     "warningTitle": "考勤异常预警",
     "rateCardTitle": "出勤率汇总",

src/shared/i18n/messages/zh-CN/elective.json

@@ -95,7 +95,19 @@
     "alreadySelected": "您已选过此课程",
     "selectionClosed": "选课已关闭",
     "gradeMismatch": "您的年级不符合课程要求",
+    "scheduleConflict": "时间与已选课程冲突",
+    "creditExceeded": "学分超限（{current}/{max}）",
     "invalidForm": "表单数据无效",
     "unexpected": "发生未知错误"
+  },
+  "messages": {
+    "created": "选修课程已创建",
+    "updated": "选修课程已更新",
+    "deleted": "选修课程已删除",
+    "selectionOpened": "选课已开放",
+    "selectionClosed": "选课已关闭",
+    "lotteryCompleted": "抽签完成：录取 {enrolled} 人，候补 {waitlist} 人",
+    "courseDropped": "已退选课程",
+    "ownershipCheckFailed": "归属校验失败"
   }
 }

src/shared/i18n/messages/zh-CN/textbooks.json

@@ -58,7 +58,8 @@
     "noChapters": "暂无章节",
     "noChaptersDesc": "这本教材还没有章节。",
     "sidebar": "目录与知识点",
-    "openSidebar": "打开目录"
+    "openSidebar": "打开目录",
+    "prepareLesson": "为此课文备课"
   },
   "dialog": {
     "create": {
@@ -91,6 +92,7 @@
       "titlePlaceholder": "例如：第一章：入门",
       "toggle": "展开/折叠",
       "orderUpdated": "顺序已更新",
+      "orderUpdateFailed": "顺序更新失败",
       "cancel": "取消",
       "dragHandle": "拖拽排序"
     },
@@ -251,7 +253,8 @@
     "toolbar": {
       "search": "搜索知识点",
       "filterByChapter": "按章节筛选",
-      "resetView": "重置视图"
+      "resetView": "重置视图",
+      "refreshing": "刷新中..."
     },
     "empty": {
       "noPrerequisites": "暂无前置依赖关系",