Fix gamehub connection + config

Shogi.UI/Shared/GameHubNode.cs

@@ -16,7 +16,7 @@ public class GameHubNode : IAsyncDisposable
 		}
 
 		this.hubConnection = new HubConnectionBuilder()
-			.WithUrl(new Uri($"{baseUrl}/gamehub", UriKind.Absolute), options =>
+			.WithUrl(new Uri(new Uri(baseUrl, UriKind.Absolute), "gamehub"), options =>
 			{
 				options.HttpMessageHandlerFactory = handler => new CookieCredentialsMessageHandler { InnerHandler = handler };
 				options.SkipNegotiation = true;