feat(parent-portal): 完成参考项目(CICD)家长端功能全量覆盖 - 9 新页面 + 3 页面增强 + 763 测试通过

## 变更内容

### P0 高优先级新页面
- /parent/leave: 请假表单(react-hook-form + Zod) + 历史列表(状态筛选)
- /parent/grades/report-card: 报告卡(学年/学期筛选 + 打印 + 教师评语)
- /parent/children/[studentId]: 子女详情聚合页(5 Tab: overview/homework/grades/exams/schedule)

### P1 中优先级新页面
- /parent/error-book: 错题本(5 项统计 + Top 错题 + 薄弱知识点)
- /parent/diagnostic: 诊断报告(掌握度摘要 + 已发布诊断报告)
- /parent/practice: 练习统计(4 项统计 + 练习历史)

### P2 低优先级新页面
- /parent/course-plans + [id]: 课程计划列表 + 详情(章节列表)
- /parent/lesson-plans + [planId]/view: 备课列表(学科筛选) + 只读详情
- /parent/elective: 选修课(分类色点 + 状态徽标)

### P3 现有页面增强
- /parent/dashboard: ParentAttentionBanner + 多子女卡片网格 + 趋势图标 + 逾期高亮
- /parent/attendance: AttendanceRateCard + AttendanceWarningBanner + 月份导航
- /parent/grades: GrowthArchiveChart + ExportGradesButton + 班级均对比线

### 基础设施
- types/index.ts: +20 新类型(LeaveRequest/ReportCard/ErrorBookStats/DiagnosticReport/PracticeStats/CoursePlan/LessonPlan/ElectiveSelection/ChildDetail/ScheduleItem 等)
- operations.ts: +19 GraphQL operations(17 query + 2 mutation)
- fixtures.ts: +18 mock 数据集
- handlers.ts: +19 MSW GraphQL handler

### 质量校验
- typecheck: 0 错误
- lint: 0 错误
- test: 71 文件 / 763 测试全部通过(从 413 增至 763, +350 测试)

### 文档
- workline.md: 新增 §7 参考项目(CICD)差距分析与实现安排 + §7.3-7.5 实现进度与覆盖完成度

### 设计决策
- 保留当前"单子女切换"范式(MultiChildTabBar + useChildSwitcher),不迁移到"多子女同屏对比"
- 仪表盘除外:已增强为多子女卡片网格并列展示
- 参考项目所有 11 个家长端页面功能已 100% 覆盖

Refs: ARB-020 §22, ARB-022 §24.4

apps/parent-portal/src/components/AttendanceCalendar.tsx

@@ -2,6 +2,7 @@
 // 依据：02-architecture-design.md §15.5 AttendanceCalendar 设计
 // - 月历视图，每天用颜色点标记考勤状态
 // - present=success / late=warning / absent=danger / leave=ink-subtle
+// - 支持月份导航（可选 month + onMonthChange props）
 
 "use client";
 
@@ -11,6 +12,10 @@ import { cn } from "@/lib/utils";
 
 interface AttendanceCalendarProps {
   records: AttendanceRecord[];
+  /** YYYY-MM 格式，未传则使用当前月 */
+  month?: string;
+  /** 月份切换回调，传入则显示导航按钮 */
+  onMonthChange?: (month: string) => void;
 }
 
 const STATUS_STYLES: Record<AttendanceRecord["status"], string> = {
@@ -29,11 +34,34 @@ const STATUS_LABELS: Record<AttendanceRecord["status"], string> = {
 
 const WEEKDAYS = ["日", "一", "二", "三", "四", "五", "六"];
 
-export function AttendanceCalendar({ records }: AttendanceCalendarProps) {
-  const { year, month, days, recordMap } = useMemo(() => {
+function parseMonth(month: string): { year: number; month: number } {
+  const [yearStr, monthStr] = month.split("-");
+  return {
+    year: parseInt(yearStr ?? "0", 10),
+    month: parseInt(monthStr ?? "1", 10) - 1,
+  };
+}
+
+function formatMonth(year: number, month: number): string {
+  return `${year}-${String(month + 1).padStart(2, "0")}`;
+}
+
+function shiftMonth(month: string, delta: number): string {
+  const { year, month: m } = parseMonth(month);
+  const date = new Date(year, m + delta, 1);
+  return formatMonth(date.getFullYear(), date.getMonth());
+}
+
+export function AttendanceCalendar({
+  records,
+  month,
+  onMonthChange,
+}: AttendanceCalendarProps) {
+  const { year, month: monthLabel, days, recordMap } = useMemo(() => {
     const now = new Date();
-    const y = now.getFullYear();
-    const m = now.getMonth();
+    const target = month ? parseMonth(month) : { year: now.getFullYear(), month: now.getMonth() };
+    const y = target.year;
+    const m = target.month;
     const firstDay = new Date(y, m, 1);
     const lastDay = new Date(y, m + 1, 0);
     const startWeekday = firstDay.getDay();
@@ -50,7 +78,7 @@ export function AttendanceCalendar({ records }: AttendanceCalendarProps) {
     }
 
     return { year: y, month: m, days: dayCells, recordMap: map };
-  }, [records]);
+  }, [records, month]);
 
   // 统计
   const stats = useMemo(() => {
@@ -64,9 +92,31 @@ export function AttendanceCalendar({ records }: AttendanceCalendarProps) {
   return (
     <div className="rounded border border-rule bg-paper-elevated p-4">
       <div className="flex items-center justify-between">
-        <h3 className="font-serif text-base">
-          {year}年{month + 1}月考勤
-        </h3>
+        <div className="flex items-center gap-2">
+          {onMonthChange && (
+            <button
+              type="button"
+              onClick={() => onMonthChange(shiftMonth(formatMonth(year, monthLabel), -1))}
+              className="rounded px-2 py-1 text-sm text-ink-muted hover:text-ink"
+              aria-label="上一月"
+            >
+              ‹
+            </button>
+          )}
+          <h3 className="font-serif text-base">
+            {year}年{monthLabel + 1}月考勤
+          </h3>
+          {onMonthChange && (
+            <button
+              type="button"
+              onClick={() => onMonthChange(shiftMonth(formatMonth(year, monthLabel), 1))}
+              className="rounded px-2 py-1 text-sm text-ink-muted hover:text-ink"
+              aria-label="下一月"
+            >
+              ›
+            </button>
+          )}
+        </div>
         <div className="flex gap-3 text-xs">
           {(Object.keys(STATUS_LABELS) as AttendanceRecord["status"][]).map(
             (s) => (
@@ -98,7 +148,7 @@ export function AttendanceCalendar({ records }: AttendanceCalendarProps) {
             if (day === null) {
               return <div key={idx} className="aspect-square" />;
             }
-            const dateStr = `${year}-${String(month + 1).padStart(2, "0")}-${String(day).padStart(2, "0")}`;
+            const dateStr = `${year}-${String(monthLabel + 1).padStart(2, "0")}-${String(day).padStart(2, "0")}`;
             const record = recordMap.get(dateStr);
             return (
               <div