feat(alarms): scripted condition Quality from worst-of-input tag quality (#478)

Layer 3 of #477: a scripted alarm's condition Quality now reflects the WORST
quality across its input tags, mirroring the native OT semantic (#477 L2).

Plumbing (quality was silently discarded twice on the live path):
- VirtualTagActor.DependencyValueChanged gains Quality (defaulted Good); the
  DependencyMuxActor forwards the published AttributeValuePublished.Quality it
  already carried; ScriptedAlarmHostActor.OnDependencyChanged pushes the real
  quality into the engine (was hardcoded 0u/Good).

Engine (Core.ScriptedAlarms):
- ScriptedAlarmEngine computes worst-of-input quality each eval (skipping
  not-yet-published inputs, which are a readiness concern, not a quality signal)
  and carries it on ScriptedAlarmEvent.WorstInputStatusCode.
- A real transition carries the current worst quality so ToSnapshot's full
  snapshot doesn't clobber quality back to Good (e.g. transition while Uncertain).
- A Bad input freezes the condition (no transition), like a comms-lost native
  driver; a quality-bucket change with no transition emits the new
  EmissionKind.QualityChanged, routed to the existing #477-L2
  AlarmQualityUpdate -> WriteAlarmQuality node path (quality only, no /alerts
  row, no historian write). ScriptedAlarmSource skips QualityChanged so it never
  fabricates a phantom IAlarmSource event.

Host: ToSnapshot maps WorstInputStatusCode -> OpcUaQuality; OnEngineEmission
routes QualityChanged out of band.

Tests (TDD, RED-first): engine worst-carry + Bad/restore QualityChanged +
unchanged-bucket-no-emit; source swallows QualityChanged; mux forwards quality;
host Bad-dep -> AlarmQualityUpdate(no alerts) + transition snapshot carries worst.
Docs: AlarmTracking.md Layer-3 section + design doc.

Closes #478

src/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmSource.cs

@@ -81,6 +81,11 @@ public sealed class ScriptedAlarmSource : IAlarmSource, IDisposable
     {
         if (_disposed) return;
 
+        // #478 — QualityChanged is a source-quality annotation, not a Part 9 state change. It is delivered
+        // out of band via the dedicated WriteAlarmQuality node path; surfacing it here would fabricate a
+        // phantom AlarmEventArgs that materializes / historizes a condition. Swallow it.
+        if (evt.Emission == EmissionKind.QualityChanged) return;
+
         foreach (var sub in _subscriptions.Values)
         {
             if (!Matches(sub, evt)) continue;