feat(server): route OPC UA Part 9 AddComment to ScriptedAlarmEngine

RouteScriptedAlarmMethodCalls now handles ConditionType.AddComment
alongside Acknowledge/Confirm, dispatching to engine.AddCommentAsync.
An empty comment is rejected by the Part 9 state machine and surfaced
as BadInvalidArgument. MapCallOperation gates AddComment at the
AlarmAcknowledge tier — there is no dedicated AddComment permission bit.

Closes phase-7-status.md Gap 1: all Part 9 alarm methods now route to
the engine. Adds 3 unit tests.

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

tests/Server/ZB.MOM.WW.OtOpcUa.Server.Tests/CallGatingTests.cs

@@ -33,6 +33,14 @@ public sealed class CallGatingTests
             .ShouldBe(OpcUaOperation.AlarmConfirm);
     }
 
+    [Fact]
+    public void MapCallOperation_AddComment_maps_to_AlarmAcknowledge()
+    {
+        // AddComment has no dedicated permission bit; it gates at the Acknowledge tier.
+        DriverNodeManager.MapCallOperation(MethodIds.ConditionType_AddComment)
+            .ShouldBe(OpcUaOperation.AlarmAcknowledge);
+    }
+
     [Fact]
     public void MapCallOperation_generic_method_maps_to_Call()
     {