fix(admin): 修复排课周视图周区间错位一天（zh-cn 下 weekday(1) 是周二）

apps/admin/src/pages/Schedules/index.tsx

@@ -46,7 +46,9 @@ interface ScheduleSyncResult {
 const SchedulesPage: React.FC = () => {
   const { hasPermission } = usePermission();
   const [viewMode, setViewMode] = useState<'week' | 'month'>('week');
-  const [viewDate, setViewDate] = useState<Dayjs>(() => dayjs().weekday(1).startOf('day'));
+  const [viewDate, setViewDate] = useState<Dayjs>(() =>
+    dayjs().subtract((dayjs().day() + 6) % 7, 'day').startOf('day'),
+  );
   const [selectedDate, setSelectedDate] = useState<Dayjs | null>(null);
   const [classTeachers, setClassTeachers] = useState<ClassTeacherOption[]>([]);
   const [classTeachersLoading, setClassTeachersLoading] = useState(false);
@@ -124,7 +126,11 @@ const SchedulesPage: React.FC = () => {
     }
   };
 
-  const weekStart = useMemo(() => viewDate.weekday(1).startOf('day'), [viewDate]);
+  // 本周一：day() 与 locale 无关（0=周日…6=周六），(day()+6)%7 即距周一的天数；勿用 weekday(1)（zh-cn 下是周二）
+  const weekStart = useMemo(
+    () => viewDate.subtract((viewDate.day() + 6) % 7, 'day').startOf('day'),
+    [viewDate],
+  );
   const monthStart = useMemo(() => viewDate.startOf('month'), [viewDate]);
   const weekEnd = useMemo(() => weekStart.add(6, 'day'), [weekStart]);
   const weekNum = useMemo(() => weekStart.week(), [weekStart]);