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/Pages/Play/GameBoard/GameBoard.razor

@@ -0,0 +1,76 @@
+@using Shogi.Contracts.Api
+@using Shogi.Contracts.Types
+@using System.Text.RegularExpressions
+@using System.Security.Claims
+
+@implements IDisposable
+@inject ShogiApi ShogiApi
+@inject PromotePrompt PromotePrompt
+@inject GameHubNode hubNode
+@inject NavigationManager navigator
+
+@if (session == null)
+{
+	<EmptyGameBoard />
+}
+else if (isSpectating)
+{
+	<SpectatorGameBoard Session="session" />
+}
+else
+{
+	<SeatedGameBoard Perspective="perspective" Session="session" />
+}
+
+
+@code {
+	[CascadingParameter]
+	private Task<AuthenticationState> authenticationState { get; set; }
+
+	[Parameter]
+	[EditorRequired]
+	public string SessionId { get; set; } = string.Empty;
+
+	Session? session;
+	private WhichPlayer perspective;
+	private bool isSpectating;
+	private List<IDisposable> disposables = new List<IDisposable>(2);
+
+	protected override void OnInitialized()
+	{
+		navigator.RegisterLocationChangingHandler((a) => new ValueTask(hubNode.Unsubscribe(SessionId)));
+		disposables.Add(hubNode.OnSessionJoined(async () => await FetchSession()));
+		disposables.Add(hubNode.OnPieceMoved(async () => await FetchSession()));
+	}
+
+	protected override async Task OnParametersSetAsync()
+	{
+		await hubNode.Subscribe(SessionId);
+		await FetchSession();
+	}
+
+	async Task FetchSession()
+	{
+		if (!string.IsNullOrWhiteSpace(SessionId))
+		{
+			this.session = await ShogiApi.GetSession(SessionId);
+			if (this.session != null)
+			{
+				var state = await authenticationState;
+				var accountId = state.User.Claims.First(c => c.Type == ClaimTypes.Name).Value;
+				this.perspective = accountId == session.Player1 ? WhichPlayer.Player1 : WhichPlayer.Player2;
+				this.isSpectating = !(accountId == this.session.Player1 || accountId == this.session.Player2);
+			}
+			StateHasChanged();
+		}
+	}
+
+	public void Dispose()
+	{
+		foreach (var d in disposables)
+		{
+			d.Dispose();
+		}
+		disposables.Clear();
+	}
+}