fix(opcuaclient): review fixes - drop driver-side OperationLimits chunking (SDK batches), diagnostics as OTel counter, safe discovery selection, options validation at load (#273 #275 #276 #277 #278)

Claude-Session: https://claude.ai/code/session_01Ef2ozxS7QPanGT8uoATbTe

tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/OpcUaClientDriverPageFormSerializationTests.cs

@@ -170,13 +170,13 @@ public sealed class OpcUaClientDriverPageFormSerializationTests
             SubscriptionLifetimeCount = 600,
             SubscriptionMaxNotificationsPerPublish = 500,
             SubscriptionPriority = 9,
-            HonorServerOperationLimits = false,
             CertificateValidation = new OpcUaCertificateValidationOptions
             {
                 RejectUnknownRevocationStatus = true,
                 IssuerStorePath = "/pki/issuers",
             },
             DiscoveryUrl = "opc.tcp://lds:4840",
+            DiscoveryServerUri = "urn:plant:line1",
         };
 
         var back = OpcUaClientDriverForm.OpcUaClientFormModel.FromRecord(original).ToRecord([]);
@@ -186,7 +186,7 @@ public sealed class OpcUaClientDriverPageFormSerializationTests
         back.SubscriptionLifetimeCount.ShouldBe(600u);
         back.SubscriptionMaxNotificationsPerPublish.ShouldBe(500u);
         back.SubscriptionPriority.ShouldBe((byte)9);
-        back.HonorServerOperationLimits.ShouldBeFalse();
+        back.DiscoveryServerUri.ShouldBe("urn:plant:line1");
         back.CertificateValidation.RejectUnknownRevocationStatus.ShouldBeTrue();
         back.CertificateValidation.IssuerStorePath.ShouldBe("/pki/issuers");
         back.DiscoveryUrl.ShouldBe("opc.tcp://lds:4840");
@@ -196,7 +196,6 @@ public sealed class OpcUaClientDriverPageFormSerializationTests
         def.SubscriptionPublishingInterval.ShouldBeNull();
         def.SubscriptionKeepAliveCount.ShouldBe(10u);
         def.SubscriptionLifetimeCount.ShouldBe(1000u);
-        def.HonorServerOperationLimits.ShouldBeTrue();
         def.DiscoveryUrl.ShouldBeNull();
     }