feat: add class roster export and attendance stats export

- GET /classes/:id/roster/export — Excel export with 姓名/学号/加入日期/状态
- GET /attendance-records/export — Excel export with 姓名/班级/日期/时段/状态/来源/备注/打卡时间
- Add findAllForExport to AttendanceService (no pagination)
- Both use ExcelJS following classrooms controller downloadTemplate pattern

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

@@ -218,4 +218,42 @@ export class AttendanceService {
     record.matchStatus = '已匹配';
     return this.dingRawRepo.save(record);
   }
+
+  // ── Export all attendance records with filters (no pagination) ──
+  async findAllForExport(query: {
+    classId?: number;
+    dateFrom?: string;
+    dateTo?: string;
+    session?: string;
+    status?: string;
+    source?: string;
+  }) {
+    const qb = this.attendanceRepo
+      .createQueryBuilder('ar')
+      .leftJoinAndSelect('ar.student', 'student')
+      .leftJoinAndSelect('ar.class', 'class');
+
+    if (query.classId) {
+      qb.andWhere('ar.classId = :classId', { classId: query.classId });
+    }
+    if (query.dateFrom) {
+      qb.andWhere('ar.attendanceDate >= :dateFrom', { dateFrom: query.dateFrom });
+    }
+    if (query.dateTo) {
+      qb.andWhere('ar.attendanceDate <= :dateTo', { dateTo: query.dateTo });
+    }
+    if (query.session) {
+      qb.andWhere('ar.session = :session', { session: query.session });
+    }
+    if (query.status) {
+      qb.andWhere('ar.status = :status', { status: query.status });
+    }
+    if (query.source) {
+      qb.andWhere('ar.source = :source', { source: query.source });
+    }
+
+    qb.orderBy('ar.attendanceDate', 'DESC').addOrderBy('ar.createdAt', 'DESC');
+
+    return qb.getMany();
+  }
 }