v0.5.3 - ACM-6: Fix MKP race condition
ACM-6: Fix MKP pin race condition in acm_load
pendingMkp was a Map<sessionID, single entry>, causing back-to-back or parallel acm_load calls to overwrite each other before the session.updated event fired.
Changed to Map<sessionID, Array<...>> and drain the full queue in the event handler.