Improve gateway reliability and dashboard docs

clients/dotnet/MxGateway.Client/MxGatewayClientOptions.cs

@@ -21,6 +21,8 @@ public sealed class MxGatewayClientOptions
 
     public TimeSpan DefaultCallTimeout { get; init; } = TimeSpan.FromSeconds(30);
 
+    public TimeSpan? StreamTimeout { get; init; }
+
     public MxGatewayClientRetryOptions Retry { get; init; } = new();
 
     public ILoggerFactory? LoggerFactory { get; init; }
@@ -57,6 +59,27 @@ public sealed class MxGatewayClientOptions
                 "The default call timeout must be greater than zero.");
         }
 
+        if (StreamTimeout is not null && StreamTimeout <= TimeSpan.Zero)
+        {
+            throw new ArgumentOutOfRangeException(
+                nameof(StreamTimeout),
+                "The stream timeout must be greater than zero when configured.");
+        }
+
+        if (UseTls && Endpoint.Scheme != Uri.UriSchemeHttps)
+        {
+            throw new ArgumentException(
+                "UseTls requires an https gateway endpoint.",
+                nameof(Endpoint));
+        }
+
+        if (!UseTls && Endpoint.Scheme == Uri.UriSchemeHttps)
+        {
+            throw new ArgumentException(
+                "An https gateway endpoint requires UseTls.",
+                nameof(Endpoint));
+        }
+
         Retry.Validate();
     }
 }