feat(alarms): exact OPC UA severity + per-condition quality on native alarm events (#626)

AlarmEventArgs gains optional OpcUaSeverity (supersedes the four-bucket mapping, clamped
1..1000) and QualityStatusCode (projected onto the condition's Quality). An Unspecified-kind
event carrying a quality is a quality-only annotation: the host updates the condition but
publishes no alerts row. Both default null, so every existing native source is unchanged.

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/Drivers/DriverHostActor.cs

@@ -1811,8 +1811,11 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers, IWithUnboundedS
             _opcUaPublishActor.Tell(new ZB.MOM.WW.OtOpcUa.Runtime.OpcUa.OpcUaPublishActor.AlarmStateUpdate(
                 nodeId, snapshot, msg.Args.SourceTimestampUtc, n.Realm));
 
-            // Only the Primary publishes the cluster-wide alerts transition (see the gate above).
-            if (!serviceAlertsAsPrimary) continue;
+            // Only the Primary publishes the cluster-wide alerts transition (see the gate above). A quality-only
+            // annotation (#626: e.g. an MTConnect condition gone Unavailable while already Normal) is not an
+            // alarm transition at all — the condition write above carries it; an alerts row would read as
+            // "Activated" for something that never activated.
+            if (!serviceAlertsAsPrimary || msg.Args.IsQualityOnly) continue;
 
             var meta = _alarmMetaByNodeId.TryGetValue(nodeId, out var m)
                 ? m : (EquipmentId: nodeId, Name: nodeId, AlarmType: "AlarmCondition", HistorizeToAveva: (bool?)null,