- dingtalk.service.ts syncOneUser: find Student by userId before mapping, use Student.id (not User.id) as studentId FK - sync.service.ts importDingTalkUsers: type coercion for studentId (method deleted in Task 4, minimal compile fix) - schedule-sync.service.ts getStatus: remove broken teacher mapping query (teacher scheduling deprecated); hardcode mappedTeachers=0, totalTeachers=0