fix(virtualtags): consume VirtualTag.TimerIntervalMs; add VirtualTagNoEffectiveTrigger gate (lmxopcua#783)

Choice: implement the timer (option a). The field was designed and promised as a
working trigger: the entity doc says ChangeTriggered and TimerIntervalMs together
realize the trigger model, the DB check constraint requires ChangeTriggered OR a
timer >= 50, the AdminUI virtual-tag modal exposes "TimerIntervalMs (optional)" and
UnsTreeService rejects a tag with neither, and the 2026-06-08 design specified
"ChangeTriggered OR TimerIntervalMs>=50". Only the runtime never honoured it (the
standalone TimerTriggerScheduler was deleted in #603), so a timer-only tag sat at
BadWaitingForInitialData forever.

- EquipmentVirtualTagPlan carries ChangeTriggered/TimerIntervalMs (in equality, so
  an edit respawns the child); both the composer and the artifact decode fill them.
- VirtualTagActor schedules a repeating tick (PreStart, cancelled in PostStop,
  clamped to the 50 ms floor). ChangeTriggered=false makes the timer the only
  trigger. A tick during an in-flight async run (#779) is dropped, not stashed, so
  slow scripts never build a backlog of runs.
- DraftValidator VirtualTagNoEffectiveTrigger (hard error, same severity as
  CalculationNoEffectiveTrigger): no timer and no change trigger with a literal
  ctx.GetTag read.

Tests: VirtualTagActorTimerTests, DraftValidatorVirtualTagTriggerTests, artifact
decode test. Mutation-checked: no scheduling, stashing ticks, no cancel in
PostStop, and removing the validator call each fail a test.

Claude-Session: https://claude.ai/code/session_01GT67AEHd2Acv1YPwGfXEoV

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

@@ -1416,6 +1416,12 @@ internal sealed class ParsedDeploymentArtifact : IDisposable
                 && (hEl.ValueKind == JsonValueKind.True || hEl.ValueKind == JsonValueKind.False)
                 && hEl.GetBoolean();
 
+            // Triggers (lmxopcua#783): entity defaults when absent/malformed — change-triggered, no timer.
+            var changeTriggered = !(el.TryGetProperty("ChangeTriggered", out var ctEl)
+                && ctEl.ValueKind == JsonValueKind.False);
+            int? timerMs = el.TryGetProperty("TimerIntervalMs", out var tmEl)
+                && tmEl.ValueKind == JsonValueKind.Number && tmEl.TryGetInt32(out var tmv) ? tmv : null;
+
             // Substitute each {{equip}}/<RefName> with the owning equipment's backing RawPath BEFORE
             // extracting refs, so both Expression and DependencyRefs are machine-specific — byte-parity
             // with AddressSpaceComposer.Compose.
@@ -1430,7 +1436,9 @@ internal sealed class ParsedDeploymentArtifact : IDisposable
                 DataType: dataType ?? "BaseDataType",
                 Expression: expanded,
                 DependencyRefs: EquipmentScriptPaths.ExtractDependencyRefs(expanded),
-                Historize: historize));
+                Historize: historize,
+                ChangeTriggered: changeTriggered,
+                TimerIntervalMs: timerMs));
         }
 
         result.Sort((a, b) =>