Pre-materialize ViewerEventCounters before the mission loop so in-flight
Adds are visible to subsequent iterations sharing the same (EventKey, Period);
add optional ImportMission.Slot field so callers can supply weekly slot identity
(2 or 3) rather than relying on the LotType-derived default of 1.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
c253930d59