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

@@ -31,7 +31,12 @@
     "excused": "Excused",
     "attendanceRate": "Attendance Rate",
     "lateRate": "Late Rate",
-    "recentRecords": "Recent Records"
+    "recentRecords": "Recent Records",
+    "studentRecords": "Student Records",
+    "noClasses": "No classes",
+    "noClassesDescription": "You don't have any classes yet.",
+    "noData": "No data",
+    "noDataDescription": "No attendance data available for this class."
   },
   "filters": {
     "class": "Class",
@@ -66,7 +71,10 @@
     "selectClass": "Select Class",
     "selectDate": "Select Date",
     "noStudents": "No students in this class",
+    "description": "Select a class and date, then mark attendance for each student.",
     "confirmDelete": "Are you sure you want to delete this attendance record?",
+    "confirmClassSwitch": "Switching class will discard unsaved changes. Continue?",
+    "confirmClassSwitchAction": "Switch Class",
     "saved": "Attendance saved",
     "updated": "Attendance updated",
     "deleted": "Attendance record deleted"
@@ -86,10 +94,34 @@
   "parent": {
     "warningTitle": "Attendance Warnings",
     "rateCardTitle": "Attendance Rate Summary",
-    "calendarTitle": "Attendance Calendar",
+    "calendarTitle": "Attendance calendar for {name}",
+    "calendarFor": "{name}'s Calendar",
+    "prevMonth": "Previous month",
+    "nextMonth": "Next month",
     "noWarnings": "No attendance warnings",
     "absentWarning": "{count} absence(s)",
+    "absentHighSeverity": "{count} absences recorded. Consider contacting the homeroom teacher.",
     "lateWarning": "{count} late arrival(s)",
-    "lowRateWarning": "Attendance rate {rate}% below threshold"
+    "lowRateWarning": "Attendance rate {rate}% below threshold",
+    "contactHomeroom": "Consider contacting the homeroom teacher for details.",
+    "rateExcellent": "Excellent",
+    "rateNeedsAttention": "Needs attention",
+    "rateBelowStandard": "Below standard",
+    "children": "Children",
+    "linked": "linked",
+    "thisPeriod": "this period",
+    "noChildrenTitle": "No children linked",
+    "noChildrenDescription": "Your account is not linked to any student accounts yet. Please contact the school administrator.",
+    "compareDescription": "Compare attendance across all your children. For single-child details, open the child's detail page.",
+    "noRecordsDescription": "Your children don't have any attendance records yet.",
+    "weekday": {
+      "sun": "Sun",
+      "mon": "Mon",
+      "tue": "Tue",
+      "wed": "Wed",
+      "thu": "Thu",
+      "fri": "Fri",
+      "sat": "Sat"
+    }
   }
 }

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

@@ -8,6 +8,8 @@
   },
   "description": {
     "adminList": "Manage elective courses, open/close selection and lottery.",
+    "create": "Create a new elective course.",
+    "edit": "Update elective course details.",
     "teacher": "View and manage the elective courses you teach.",
     "student": "Browse available courses and make selections."
   },
@@ -21,6 +23,9 @@
     "fcfs": "First Come First Served",
     "lottery": "Lottery"
   },
+  "filters": {
+    "allStatuses": "All Modes"
+  },
   "selectionStatus": {
     "selected": "Selected",
     "enrolled": "Enrolled",

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

@@ -31,7 +31,12 @@
     "excused": "请假",
     "attendanceRate": "出勤率",
     "lateRate": "迟到率",
-    "recentRecords": "最近记录"
+    "recentRecords": "最近记录",
+    "studentRecords": "学生记录",
+    "noClasses": "暂无班级",
+    "noClassesDescription": "您目前没有任何班级。",
+    "noData": "暂无数据",
+    "noDataDescription": "该班级暂无考勤数据。"
   },
   "filters": {
     "class": "班级",
@@ -66,7 +71,10 @@
     "selectClass": "选择班级",
     "selectDate": "选择日期",
     "noStudents": "该班级暂无学生",
+    "description": "选择班级和日期，然后为每位学生标记考勤。",
     "confirmDelete": "确定删除此条考勤记录吗？",
+    "confirmClassSwitch": "切换班级将丢弃未保存的修改，是否继续？",
+    "confirmClassSwitchAction": "切换班级",
     "saved": "考勤已保存",
     "updated": "考勤已更新",
     "deleted": "考勤记录已删除"
@@ -86,10 +94,34 @@
   "parent": {
     "warningTitle": "考勤异常预警",
     "rateCardTitle": "出勤率汇总",
-    "calendarTitle": "考勤月历",
+    "calendarTitle": "{name} 的考勤月历",
+    "calendarFor": "{name} 的月历",
+    "prevMonth": "上个月",
+    "nextMonth": "下个月",
     "noWarnings": "暂无考勤异常",
     "absentWarning": "{count} 次缺勤",
+    "absentHighSeverity": "已记录 {count} 次缺勤，建议联系班主任了解情况。",
     "lateWarning": "{count} 次迟到",
-    "lowRateWarning": "出勤率 {rate}% 低于阈值"
+    "lowRateWarning": "出勤率 {rate}% 低于阈值",
+    "contactHomeroom": "如需了解详情，请联系班主任。",
+    "rateExcellent": "优秀",
+    "rateNeedsAttention": "需要关注",
+    "rateBelowStandard": "未达标",
+    "children": "子女",
+    "linked": "已关联",
+    "thisPeriod": "本周期",
+    "noChildrenTitle": "尚未关联子女",
+    "noChildrenDescription": "您的账号尚未关联任何学生账号，请联系学校管理员。",
+    "compareDescription": "对比所有子女的考勤情况。如需查看单个子女详情，请进入子女详情页。",
+    "noRecordsDescription": "您的子女暂无任何考勤记录。",
+    "weekday": {
+      "sun": "周日",
+      "mon": "周一",
+      "tue": "周二",
+      "wed": "周三",
+      "thu": "周四",
+      "fri": "周五",
+      "sat": "周六"
+    }
   }
 }

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

@@ -8,6 +8,8 @@
   },
   "description": {
     "adminList": "管理选修课程、开放/关闭选课与抽签。",
+    "create": "创建新的选修课程。",
+    "edit": "更新选修课程详情。",
     "teacher": "查看和管理您教授的选修课程。",
     "student": "浏览可选课程并进行选课。"
   },
@@ -21,6 +23,9 @@
     "fcfs": "先到先得",
     "lottery": "抽签"
   },
+  "filters": {
+    "allStatuses": "全部模式"
+  },
   "selectionStatus": {
     "selected": "已选",
     "enrolled": "已录取",