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/Part9StateMachine.cs

@@ -377,4 +377,9 @@ public enum EmissionKind
     Enabled,
     Disabled,
     CommentAdded,
+    /// <summary>#478 — the worst-of-input source quality changed bucket (Good/Uncertain/Bad) with no
+    /// accompanying Part 9 state transition. Delivered out of band via the dedicated
+    /// <c>WriteAlarmQuality</c> node path, never through the <c>IAlarmSource</c> fan-out (it is not a
+    /// state change and must not materialize or historize a condition).</summary>
+    QualityChanged,
 }