Replace custom socket implementation with SignalR.

Replace MSAL and custom cookie auth with Microsoft.Identity.EntityFramework
Also some UI redesign to accommodate different login experience.

Shogi.UI/Shared/GameHubNode.cs

@@ -0,0 +1,59 @@
+using Microsoft.AspNetCore.SignalR.Client;
+using Shogi.UI.Identity;
+using System.Diagnostics;
+
+namespace Shogi.UI.Shared;
+
+public class GameHubNode : IAsyncDisposable
+{
+	private readonly HubConnection hubConnection;
+
+	public GameHubNode()
+	{
+		this.hubConnection = new HubConnectionBuilder()
+			.WithUrl(new Uri("https://localhost:5001/gamehub", UriKind.Absolute), options =>
+			{
+				options.HttpMessageHandlerFactory = handler => new CookieCredentialsMessageHandler { InnerHandler = handler };
+				options.SkipNegotiation = true;
+				options.Transports = Microsoft.AspNetCore.Http.Connections.HttpTransportType.WebSockets;
+			})
+		.Build();
+	}
+
+	public bool IsConnected => this.hubConnection.State == HubConnectionState.Connected;
+
+	public async Task BeginListen()
+	{
+		if (!this.IsConnected)
+		{
+			await this.hubConnection.StartAsync();
+		}
+	}
+
+	public async Task Subscribe(string sessionId)
+	{
+		await this.hubConnection.SendAsync("Subscribe", sessionId);
+	}
+
+	public async Task Unsubscribe(string sessionId)
+	{
+		await this.hubConnection.SendAsync("Unsubscribe", sessionId);
+	}
+
+
+	public IDisposable OnSessionJoined(Func<Task> func)
+	{
+		return this.hubConnection.On("SessionJoined", func);
+	}
+
+	public IDisposable OnPieceMoved(Func<Task> func)
+	{
+		return this.hubConnection.On("PieceMoved", func);
+	}
+
+	public ValueTask DisposeAsync()
+	{
+		GC.SuppressFinalize(this);
+		return this.hubConnection.DisposeAsync();
+	}
+}