Register BAG_UPDATE_DELAYED to catch autoloot objective updates.
Autoloot bots that bypass the loot frame skip QUEST_WATCH_UPDATE,
leaving the tracker stuck at a stale count. Setting doFullQuestLogScan=true
on BAG_UPDATE_DELAYED forces a refresh on the next QUEST_LOG_UPDATE.
QuestieQuestPrivates.lua: event handler now returns nil silently when
Coordinates is nil, instead of logging a visible error. Nil coordinates
are valid for server-tracked objectives (complete N quests in zone) that
have no map pin.