Fix localhost reference.

Shogi.UI/Shared/GameHubNode.cs

@@ -1,6 +1,5 @@
 using Microsoft.AspNetCore.SignalR.Client;
 using Shogi.UI.Identity;
-using System.Diagnostics;
 
 namespace Shogi.UI.Shared;
 
@@ -8,10 +7,16 @@ public class GameHubNode : IAsyncDisposable
 {
 	private readonly HubConnection hubConnection;
 
-	public GameHubNode()
+	public GameHubNode(IConfiguration configuration)
 	{
+		var baseUrl = configuration["ShogiApiUrl"];
+		if (string.IsNullOrWhiteSpace(baseUrl))
+		{
+			throw new InvalidOperationException("ShogiApiUrl configuration is missing.");
+		}
+
 		this.hubConnection = new HubConnectionBuilder()
-			.WithUrl(new Uri("https://localhost:5001/gamehub", UriKind.Absolute), options =>
+			.WithUrl(new Uri($"{baseUrl}/gamehub", UriKind.Absolute), options =>
 			{
 				options.HttpMessageHandlerFactory = handler => new CookieCredentialsMessageHandler { InnerHandler = handler };
 				options.SkipNegotiation = true;