refactor(server): 日期/月份格式化统一改用 dayjs

- 替换散落的 toISOString().slice(0,10) / split('T')[0] / replace('T',' ')（UTC 语义用 dayjs(...).utc() 保持完全一致）
- Asia/Shanghai 固定时区日期（Intl.DateTimeFormat en-CA）改用 dayjs().utcOffset(8)
- 月份边界 first/last、daysInMonth、nextMonth、shiftDate/addDays 等改 dayjs 简洁实现
- 涉及 attendance/classes/classrooms/room/dashboard/bills/expenses/occupancies/sync/ai-chat/rental 等 28 个文件

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

@@ -3,6 +3,7 @@ import { InjectRepository } from '@nestjs/typeorm';
 import { Repository, Between } from 'typeorm';
 import { AttendanceRecord, ClassSchedule } from '../entities';
 import type { AttendanceCalendarQueryDto } from './dto/attendance.dto';
+import dayjs from '../common/dayjs';
 
 @Injectable()
 export class AttendanceCalendarService {
@@ -23,7 +24,7 @@ export class AttendanceCalendarService {
       const diff = day === 0 ? -6 : 1 - day; // Monday offset
       const monday = new Date(now);
       monday.setDate(now.getDate() + diff);
-      const mondayStr = monday.toISOString().slice(0, 10);
+      const mondayStr = dayjs(monday).utc().format('YYYY-MM-DD');
 
       return this.buildCalendar(classId, mondayStr);
     }
@@ -77,7 +78,7 @@ export class AttendanceCalendarService {
     const start = new Date(weekStart);
     const end = new Date(start);
     end.setDate(start.getDate() + 6);
-    const endStr = end.toISOString().slice(0, 10);
+    const endStr = dayjs(end).utc().format('YYYY-MM-DD');
 
     const records = await this.attendanceRepo.find({
       where: {

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

@@ -97,7 +97,7 @@ export class AttendanceGenerationService {
     const entities: AttendanceRecord[] = [];
     const end = new Date(dateTo);
     for (let d = new Date(dateFrom); d <= end; d.setDate(d.getDate() + 1)) {
-      const dateStr = d.toISOString().slice(0, 10);
+      const dateStr = dayjs(d).utc().format('YYYY-MM-DD');
       const weekDay = d.getDay() === 0 ? 7 : d.getDay();
 
       for (const sched of schedules) {
@@ -147,8 +147,8 @@ export class AttendanceGenerationService {
     sunday.setDate(monday.getDate() + 6);
     sunday.setHours(23, 59, 59, 999);
 
-    const dateFrom = startDate ?? monday.toISOString().slice(0, 10);
-    const dateTo = endDate ?? sunday.toISOString().slice(0, 10);
+    const dateFrom = startDate ?? dayjs(monday).utc().format('YYYY-MM-DD');
+    const dateTo = endDate ?? dayjs(sunday).utc().format('YYYY-MM-DD');
 
     return this.generateAttendanceFromSchedules({
       classId,

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

@@ -2,6 +2,7 @@ import { BadRequestException, Injectable, Logger } from '@nestjs/common';
 import { InjectRepository } from '@nestjs/typeorm';
 import { Repository, In } from 'typeorm';
 import { Subject, Observable } from 'rxjs';
+import dayjs from '../common/dayjs';
 import {
   DingAttendanceRaw,
   Student,
@@ -238,7 +239,7 @@ export class AttendanceImportService {
   }
 
   private formatDate(value: Date): string {
-    return value.toISOString().slice(0, 10);
+    return dayjs.utc(value).format('YYYY-MM-DD');
   }
 
   /**

apps/server/src/attendance/attendance-leave-sync.service.ts

@@ -3,6 +3,7 @@ import { InjectRepository } from '@nestjs/typeorm';
 import { Repository } from 'typeorm';
 import { DingLeaveRaw, Student, StudentDingMapping } from '../entities';
 import { DingTalkService, DingTalkLeaveResult } from '../integration/dingtalk.service';
+import dayjs from '../common/dayjs';
 
 /**
  * 钉钉请假数据同步服务。
@@ -152,7 +153,7 @@ export class AttendanceLeaveSyncService {
   }
 
   private formatDate(value: Date): string {
-    return value.toISOString().slice(0, 10);
+    return dayjs.utc(value).format('YYYY-MM-DD');
   }
 
   private async resolveStudentName(dingUserId: string): Promise<string> {

apps/server/src/attendance/attendance-records.controller.ts

@@ -6,6 +6,7 @@ import { AttendanceImportService } from './attendance-import.service';
 import { OperationLogsService } from '../operation-logs/operation-logs.service';
 import { AuthorizationService } from '../authorization';
 import { logAudit } from '../common/with-audit-log';
+import dayjs from '../common/dayjs';
 import { extractRequestInfo, type RequestInfoSource } from '../common/request-utils';
 import { RequirePermission } from '../auth/decorators/permission.decorator';
 import {
@@ -195,11 +196,11 @@ export class AttendanceRecordsController extends AttendanceControllerBase {
         source: record.source || '',
         punchDevice: record.punchDeviceName || record.punchDeviceId || '',
         punchTime: record.punchTime
-          ? record.punchTime.toISOString().replace('T', ' ').substring(0, 19)
+          ? dayjs(record.punchTime).utc().format('YYYY-MM-DD HH:mm:ss')
           : '',
         remark: record.remark || '',
         createdAt: record.createdAt
-          ? record.createdAt.toISOString().replace('T', ' ').substring(0, 19)
+          ? dayjs(record.createdAt).utc().format('YYYY-MM-DD HH:mm:ss')
           : '',
       });
     }

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

@@ -4,6 +4,7 @@ import { Repository } from 'typeorm';
 import { AttendanceRecord, AttendanceDevice } from '../entities';
 import type { AttendanceReportQueryDto } from './dto/attendance.dto';
 import { attachAttendanceDeviceMappings } from './attendance-device';
+import dayjs from '../common/dayjs';
 
 @Injectable()
 export class AttendanceReportService {
@@ -141,7 +142,7 @@ export class AttendanceReportService {
   async getAlerts(days: number = 14, threshold: number = 3, accessibleClassIds?: number[]) {
     const cutoff = new Date();
     cutoff.setDate(cutoff.getDate() - days);
-    const cutoffStr = cutoff.toISOString().slice(0, 10);
+    const cutoffStr = dayjs(cutoff).utc().format('YYYY-MM-DD');
 
     const qb = this.attendanceRepo
       .createQueryBuilder('a')

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

@@ -295,8 +295,6 @@ export class AttendanceSettlementService {
   }
 
   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).add(days, 'day').format('YYYY-MM-DD');
   }
 }