refactor(server): 日期工具统一迁入 dayjs（utc 插件），移除手写 Intl/padStart 重复实现

apps/server/src/attendance/attendance-generation.service.ts

@@ -11,6 +11,7 @@ import {
   ScheduleType,
 } from '../entities';
 import { toMinutes, isClassStudentActiveOnDate } from './attendance-time';
+import dayjs from '../common/dayjs';
 import type { BatchCreateAttendanceDto, GenerateAttendanceFromSchedulesDto, GenerateFromSchedulesDto, SaveAttendancePeriodConfigsDto } from './dto/attendance.dto';
 
 @Injectable()
@@ -162,23 +163,15 @@ export class AttendanceGenerationService {
   }
 
   private getCourseClock(date: Date): { date: string; minutes: number } {
-    const parts = Object.fromEntries(
-      new Intl.DateTimeFormat('en-CA', {
-        timeZone: 'Asia/Shanghai',
-        year: 'numeric', month: '2-digit', day: '2-digit',
-        hour: '2-digit', minute: '2-digit', hourCycle: 'h23',
-      }).formatToParts(date).filter((part) => part.type !== 'literal').map((part) => [part.type, part.value]),
-    );
+    const c = dayjs.utc(date).add(8, 'hour');
     return {
-      date: `${parts.year}-${parts.month}-${parts.day}`,
-      minutes: Number(parts.hour) * 60 + Number(parts.minute),
+      date: c.format('YYYY-MM-DD'),
+      minutes: c.hour() * 60 + c.minute(),
     };
   }
 
   private shiftDate(date: string, days: number): string {
-    const shifted = new Date(`${date}T00:00:00.000Z`);
-    shifted.setUTCDate(shifted.getUTCDate() + days);
-    return shifted.toISOString().slice(0, 10);
+    return dayjs.utc(`${date}T00:00:00.000Z`).add(days, 'day').format('YYYY-MM-DD');
   }
 
   private async ensureAttendancePeriodConfigs() {