Add MdmEnrollmentStatus, UserDeviceMdmHealthRecord types and helpers:
- getLinkedUserDevices() to load iOS devices with NanoMDM UDIDs
- getMdmEnrollmentStatusesByUdids() for bulk NanoMDM lookups
- updateUserDeviceMdmHealth() to mirror status on UserDevice
Also fix PoolConfig option casing: queryTimeout -> query_timeout.