docs(galaxy): fix stale SystemPlatform/alias/Galaxy doc comments (review follow-up)

Resolves the code-review notes on 95be607a + the AdminUI bundle: the
EnsureVariable docs (IOpcUaAddressSpaceSink, OtOpcUaNodeManager) and the Tag
entity doc no longer say 'Galaxy / SystemPlatform / alias'; the DriverHostActor
ForwardToMux comment now states the real equipment-tag value-routing gap (the
FullName→NodeId 'live values' milestone) instead of claiming Galaxy values map
straight through.

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

@@ -383,10 +383,12 @@ public sealed class DriverHostActor : ReceiveActor, IWithTimers
         // tags registered); production binds the mux via the RuntimeActors extension.
         _dependencyMux?.Tell(msg);
 
-        // Also push the value to the OPC UA sink so the materialised variable reflects live data
-        // instead of staying BadWaitingForInitialData. For SystemPlatform / Galaxy tags the variable
-        // NodeId is exactly the dot-form MXAccess reference the driver subscribed to, so the published
-        // FullReference maps straight onto the sink NodeId.
+        // Also push the value to the OPC UA sink. NOTE: equipment-tag variables are materialised with
+        // folder-scoped NodeIds (EquipmentId/FolderPath/Name), while the driver publishes keyed by
+        // FullReference (the tag's FullName). The value therefore only lands on the variable once the
+        // FullName→NodeId routing — the equipment-tag "live values" milestone — is wired; until then
+        // the variable stays BadWaitingForInitialData. (The retired SystemPlatform mirror matched only
+        // because its NodeId WAS the FullName.)
         _opcUaPublishActor?.Tell(new ZB.MOM.WW.OtOpcUa.Runtime.OpcUa.OpcUaPublishActor.AttributeValueUpdate(
             msg.FullReference, msg.Value, msg.Quality, msg.TimestampUtc));
     }