fix(core-scripted-alarms): resolve Low code-review findings (Core.ScriptedAlarms-003,006,008,010,011; -009 documented)

- Core.ScriptedAlarms-003: emit OnEvent OUTSIDE _evalGate by collecting
  pending emissions during the gate-held section and flushing them after
  release; eliminates re-entrancy deadlock the docs already promised.
- Core.ScriptedAlarms-006: track every fire-and-forget Reevaluate /
  ShelvingCheck task in _inFlight; Dispose drains the set so the engine
  no longer races store writes against teardown.
- Core.ScriptedAlarms-008: store comments as ImmutableList<AlarmComment>
  so AppendComment is O(log n) instead of O(n).
- Core.ScriptedAlarms-010: document the deliberate input-quality
  asymmetry (Uncertain drives the predicate, renders {?} in the message)
  in docs/ScriptedAlarms.md and on MessageTemplate.Resolve remarks.
- Core.ScriptedAlarms-011: propagate the no-op reason through
  TransitionResult.NoOp(state, reason) and log it from
  ScriptedAlarmEngine.ApplyAsync.
- Core.ScriptedAlarms-009 (Won't Fix per recommendation): documented the
  per-evaluation dictionary allocation in docs/v2/Galaxy.Performance.md
  with a mitigation path if a future soak surfaces pressure.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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

@@ -1,3 +1,5 @@
+using System.Collections.Immutable;
+
 namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 
 /// <summary>
@@ -17,7 +19,10 @@ namespace ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms;
 ///     <para>
 ///         <see cref="Comments"/> is append-only; comments + ack/confirm user identities
 ///         are the audit surface regulators consume. The engine never rewrites past
-///         entries.
+///         entries. The runtime type is <see cref="ImmutableList{AlarmComment}"/> so
+///         each append is O(log n) rather than the O(n) copy a plain
+///         <c>IReadOnlyList&lt;AlarmComment&gt;</c> would force on every audit-producing
+///         transition. (Core.ScriptedAlarms-008)
 ///     </para>
 /// </remarks>
 public sealed record AlarmConditionState(
@@ -36,7 +41,7 @@ public sealed record AlarmConditionState(
     DateTime? LastConfirmUtc,
     string? LastConfirmUser,
     string? LastConfirmComment,
-    IReadOnlyList<AlarmComment> Comments)
+    ImmutableList<AlarmComment> Comments)
 {
     /// <summary>Initial-load state for a newly registered alarm — everything in the "no-event" position.</summary>
     public static AlarmConditionState Fresh(string alarmId, DateTime nowUtc) => new(
@@ -55,7 +60,7 @@ public sealed record AlarmConditionState(
         LastConfirmUtc: null,
         LastConfirmUser: null,
         LastConfirmComment: null,
-        Comments: []);
+        Comments: ImmutableList<AlarmComment>.Empty);
 }
 
 /// <summary>