perf(runtime): raise opcua pinned dispatcher throughput 1 -> 100

src/Core/ZB.MOM.WW.OtOpcUa.Cluster/Resources/akka.conf

@@ -109,8 +109,15 @@ akka {
 # Pinned dispatcher used by OpcUaPublishActor (Task 44) so the OPC UA SDK sees
 # only one thread per actor instance — its session/subscription locks expect
 # strict single-threaded access.
+#
+# throughput is NOT what provides that guarantee: the PinnedDispatcher does, by
+# giving the actor its own dedicated thread. throughput only sets how many queued
+# messages drain per scheduling run, so 100 removes a mailbox re-schedule
+# round-trip per message on the hottest actor in the process with zero change to
+# concurrency. Must stay in sync with the inline HOCON copy in
+# ServiceCollectionExtensions.WithOtOpcUaRuntimeActors.
 opcua-synchronized-dispatcher {
     type = "PinnedDispatcher"
     executor = "thread-pool-executor"
-    throughput = 1
+    throughput = 100
 }

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/ServiceCollectionExtensions.cs

@@ -302,12 +302,18 @@ public static class ServiceCollectionExtensions
         // bootstrap their own HOCON (e.g. ServiceCollectionExtensionsTests) wouldn't pick it up
         // — OpcUaPublishActor.Props pins itself to opcua-synchronized-dispatcher and Akka throws
         // ConfigurationException if it doesn't exist. Prepend a fallback so the runtime extension
-        // is self-contained.
+        // is self-contained. Keep this block identical to the akka.conf one.
+        //
+        // The OPC UA SDK's single-threaded session/subscription requirement is guaranteed by the
+        // PinnedDispatcher alone (a dedicated thread per actor instance), not by throughput.
+        // throughput only sets how many queued messages drain per scheduling run, so 100 removes a
+        // mailbox re-schedule round-trip per message on the hottest actor in the process with zero
+        // change to concurrency.
         builder.AddHocon(@"
             opcua-synchronized-dispatcher {
                 type = ""PinnedDispatcher""
                 executor = ""thread-pool-executor""
-                throughput = 1
+                throughput = 100
             }
         ", HoconAddMode.Prepend);