feat(p7-02): fill opts_test.go stubs — ServerOptionsTests

Write 3 unit tests portable without a running server:
- ListenMonitoringDefault (T:2524): SetBaselineOptions propagates Host → HttpHost
- GetStorageSize (T:2576): StorageSizeJsonConverter.Parse K/M/G/T suffixes
- ClusterNameAndGatewayNameConflict (T:2571): ValidateOptions returns ErrClusterNameConfigConflict

Mark 74 opts_test.go stubs deferred: tests require either the NATS
conf-format parser (not yet ported), a running server (RunServer/NewServer),
or CLI flag-parsing infrastructure (ConfigureOptions).

Fix StorageSizeJsonConverter.Parse to return 0 for empty input,
matching Go getStorageSize("") == (0, nil).

Total unit tests: 638 passing.

dotnet/tests/ZB.MOM.NatsNet.Server.Tests/ServerOptionsTests.cs

@@ -3,6 +3,7 @@
 
 using Shouldly;
 using ZB.MOM.NatsNet.Server;
+using ZB.MOM.NatsNet.Server.Config;
 
 namespace ZB.MOM.NatsNet.Server.Tests;
 
@@ -330,4 +331,54 @@ public class ServerOptionsTests
         var r2 = ServerOptions.MergeOptions(null, flagOpts);
         r2.Port.ShouldBe(5678);
     }
+
+    /// <summary>
+    /// Mirrors TestListenMonitoringDefault — when Host is set without HTTPHost,
+    /// SetBaselineOptions should copy Host to HTTPHost.
+    /// </summary>
+    [Fact] // T:2524
+    public void ListenMonitoringDefault_ShouldSetHttpHostToHost()
+    {
+        var opts = new ServerOptions { Host = "10.0.1.22" };
+        opts.SetBaselineOptions();
+
+        opts.Host.ShouldBe("10.0.1.22");
+        opts.HttpHost.ShouldBe("10.0.1.22");
+        opts.Port.ShouldBe(ServerConstants.DefaultPort);
+    }
+
+    /// <summary>
+    /// Mirrors TestGetStorageSize — StorageSizeJsonConverter.Parse converts K/M/G/T suffixes
+    /// and returns 0 for empty input; invalid suffixes throw.
+    /// </summary>
+    [Fact] // T:2576
+    public void GetStorageSize_ShouldParseSuffixes()
+    {
+        StorageSizeJsonConverter.Parse("1K").ShouldBe(1024L);
+        StorageSizeJsonConverter.Parse("1M").ShouldBe(1048576L);
+        StorageSizeJsonConverter.Parse("1G").ShouldBe(1073741824L);
+        StorageSizeJsonConverter.Parse("1T").ShouldBe(1099511627776L);
+        StorageSizeJsonConverter.Parse("").ShouldBe(0L);
+
+        Should.Throw<FormatException>(() => StorageSizeJsonConverter.Parse("1L"));
+        Should.Throw<FormatException>(() => StorageSizeJsonConverter.Parse("TT"));
+    }
+
+    /// <summary>
+    /// Mirrors TestClusterNameAndGatewayNameConflict — when Cluster.Name != Gateway.Name,
+    /// ValidateOptions should return ErrClusterNameConfigConflict.
+    /// </summary>
+    [Fact] // T:2571
+    public void ClusterNameAndGatewayNameConflict_ShouldReturnConflictError()
+    {
+        var opts = new ServerOptions
+        {
+            Cluster = new ClusterOpts { Name = "A", Port = -1 },
+            Gateway = new GatewayOpts { Name = "B", Port = -1 },
+        };
+
+        var err = NatsServer.ValidateOptions(opts);
+        err.ShouldNotBeNull();
+        err.ShouldBe(ServerErrors.ErrClusterNameConfigConflict);
+    }
 }