perf(comms+audit): close phase-2 residuals — direct ingest path, monotonic timeouts, synthetic probe, not-reporting set, cursor-exact audit pull

src/ZB.MOM.WW.ScadaBridge.CentralUI/Services/AlarmSummaryService.cs

@@ -154,9 +154,11 @@ public sealed class AlarmSummaryService : IAlarmSummaryService
             .ThenBy(r => r.Alarm.AlarmName, StringComparer.OrdinalIgnoreCase)
             .ToList();
 
-        // The live cache is alarm-only, so it cannot enumerate "not reporting"
-        // instances — left empty here; the periodic poll (GetSiteAlarmsAsync)
-        // remains the authority for that list.
+        // Alarm rows alone cannot name the instances that failed to answer, so this pure
+        // flattening leaves the list empty. The names come from the fan-out that produced the
+        // snapshot: while the live cache is serving a site, SharedAlarmSummaryService pairs
+        // these rows with ISiteAlarmLiveCache.GetNotReportingInstances (the aggregator's own
+        // seed/reconcile result); while it is cold, GetSiteAlarmsAsync's poll supplies both.
         return new AlarmSummaryResult(orderedRows, Array.Empty<string>());
     }