PR 6.1 — OpenTelemetry traces around gw calls

In-box ActivitySource ("ZB.MOM.WW.OtOpcUa.Driver.Galaxy") wrapped around
the three gw-facing seams via decorators:

- TracedGalaxySubscriber — galaxy.subscribe_bulk / galaxy.unsubscribe_bulk
  / galaxy.stream_events spans. Stream span covers the entire stream
  lifetime with a galaxy.event_count tag (per-event spans would dominate
  the trace volume at 50k tags / 1Hz; PR 6.2 owns per-event metrics).
- TracedGalaxyDataWriter — galaxy.write spans tagged with
  galaxy.tag_count, galaxy.secured_write_count (split between FreeAccess
  /Operate vs Tune/Configure/VerifiedWrite, computed only when a listener
  is recording so the hot path stays free), galaxy.success_count.
- TracedGalaxyHierarchySource — galaxy.get_hierarchy spans tagged with
  galaxy.object_count.

GalaxyDriver.BuildProductionRuntimeAsync wraps the production seams in
the decorators. The driver itself doesn't take an OpenTelemetry package
dependency — System.Diagnostics.ActivitySource is in-box; the host
process picks the listener.

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

src/ZB.MOM.WW.OtOpcUa.Driver.Galaxy/GalaxyDriver.cs

@@ -185,8 +185,16 @@ public sealed class GalaxyDriver
         _ownedMxSession = new GalaxyMxSession(_options.MxAccess, _logger);
         await _ownedMxSession.ConnectAsync(clientOptions, cancellationToken).ConfigureAwait(false);
 
-        _subscriber = new GatewayGalaxySubscriber(_ownedMxSession);
-        _dataWriter = new GatewayGalaxyDataWriter(_ownedMxSession, _options.MxAccess.WriteUserId, _logger);
+        // PR 6.1 — wrap the gw-facing seams in tracing decorators so every Subscribe /
+        // Unsubscribe / Write / StreamEvents call emits a span on the
+        // "ZB.MOM.WW.OtOpcUa.Driver.Galaxy" ActivitySource. The host process's tracing
+        // listener (OTLP exporter, dotnet-trace, etc.) consumes these without the driver
+        // taking a dependency on the OpenTelemetry packages.
+        _subscriber = new TracedGalaxySubscriber(
+            new GatewayGalaxySubscriber(_ownedMxSession), _options.MxAccess.ClientName);
+        _dataWriter = new TracedGalaxyDataWriter(
+            new GatewayGalaxyDataWriter(_ownedMxSession, _options.MxAccess.WriteUserId, _logger),
+            _options.MxAccess.ClientName);
 
         _supervisor = new ReconnectSupervisor(
             reopen: ReopenAsync,
@@ -559,7 +567,8 @@ public sealed class GalaxyDriver
                 : null,
         };
         _ownedRepositoryClient = GalaxyRepositoryClient.Create(clientOptions);
-        return new GatewayGalaxyHierarchySource(_ownedRepositoryClient);
+        return new TracedGalaxyHierarchySource(
+            new GatewayGalaxyHierarchySource(_ownedRepositoryClient), _options.MxAccess.ClientName);
     }
 
     public void Dispose()