compartment-trigger: log all silent skip paths for diagnostics

Three skip paths previously returned shouldFire=false with no log line,
making it impossible to diagnose why historian wasn't firing at high
pressure. Added explicit logs for:

1. compartmentInProgress skip — historian already in flight
2. !hasNewRawHistory skip — dumps nextStartOrdinal, lastCompartmentEnd,
   rawMessageCount, and protectedTailStart so the missing condition is
   visible
3. usage < proactiveTriggerPercentage skip — shows the proactive floor

Behavior unchanged. Pure observability.