fix(runtime,opcuaserver): review fast-follows — event-filter throw test, loud MapKey fallback, log shape

Accumulated fast-follows from the Task 1-11 reviews. No behaviour change on the
value path.

- Strengthen OpcUaPublishActorBatchTests.Sink_throw_is_swallowed_and_logged. The
  survival assertion alone did NOT prove the catch exists: Akka's default
  supervision RESTARTS a throwing actor and the restart preserves the mailbox, so
  the follow-up message landed either way and the test passed against a build with
  no catch at all. It now asserts via EventFilter that the exception NEVER reaches
  supervision (Expect(0) on the InvalidOperationException) and that the handler's
  own Warning IS logged, keeping the survival assertion. Everything that must have
  happened goes inside the Expect(0) action — it counts matches at the end of the
  action, so an assertion left outside would race the actor and pass vacuously.
  Verified falsifiable: deleting the catch turns the test red.

- MapKey(NodeId): the non-string identifier branch collapsed to a string.Empty key
  silently. Such a key cannot match anything the manager stored, so the caller sees
  an unexplained miss rather than an error. It now logs a Utils.LogWarning naming
  the seam. Every current call site is provably string-only, so this should never
  fire.

- The two WireAlarmNotifiers Utils.LogInfo sites interpolated the RealmKey struct,
  rendering a raw struct dump. Interpolate .Id and .Realm as separate placeholders
  so log-grep patterns stay consistent with the file's other sites.

- Stale comments: the _eventNotifierSources key is a RealmKey now, not a
  namespace-qualified NodeId string; and three comments still named
  DriverHostActor.ForwardToMux, which Task 8 replaced with ForwardBatchToMux.

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/OpcUa/OpcUaPublishActor.cs

@@ -507,7 +507,7 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
             failedNodes += _applier.MaterialiseScriptedAlarms(composition);
             // Equipment-namespace tags get their own pass: ensures each signal's Variable (and any
             // FolderPath sub-folder) exists under its already-materialised equipment folder so
-            // clients can browse them. Live values are pushed by DriverHostActor.ForwardToMux after
+            // clients can browse them. Live values are pushed by DriverHostActor.ForwardBatchToMux after
             // each subscription cycle; variables show BadWaitingForInitialData only until the first
             // publish interval fires.
             failedNodes += _applier.MaterialiseEquipmentTags(composition);