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.

Tests/AcceptanceTests/TestSetup/AatTestFixture.cs

@@ -0,0 +1,114 @@
+using Microsoft.Extensions.Configuration;
+using System.Net.Http.Json;
+using System.Text.Json;
+
+namespace Shogi.AcceptanceTests.TestSetup;
+
+/// <summary>
+/// Acceptance Test fixture for tests which assert features for Microsoft accounts.
+/// </summary>
+public class AatTestFixture : IAsyncLifetime, IDisposable
+{
+	protected static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web);
+
+	private readonly string testAccountPassword;
+	private bool disposedValue;
+
+	public AatTestFixture()
+	{
+		this.Configuration = new ConfigurationBuilder()
+			.AddJsonFile("appsettings.json")
+			.AddJsonFile("appsettings.Development.json", optional: true)
+			.Build();
+
+		var baseUrl = this.Configuration["ServiceUrl"] ?? throw new InvalidOperationException();
+		this.HttpClient = new HttpClient
+		{
+			BaseAddress = new Uri(baseUrl, UriKind.Absolute)
+		};
+		this.OtherHttpClient = new HttpClient
+		{
+			BaseAddress = new Uri(baseUrl, UriKind.Absolute)
+		};
+
+		this.testAccountPassword = this.Configuration["TestUserPassword"]!;
+		if (string.IsNullOrWhiteSpace(this.testAccountPassword))
+		{
+			throw new InvalidOperationException("TestUserPassword is not configured.");
+		}
+
+	}
+
+	public IConfiguration Configuration { get; private set; }
+	public HttpClient HttpClient { get; }
+	public HttpClient OtherHttpClient { get; }
+
+	protected async Task LoginToTestAccounts()
+	{
+		var response = await this.HttpClient.PostAsJsonAsync(
+			RelativeUri("login"),
+			new
+			{
+				email = "aat-account",
+				password = this.testAccountPassword,
+			},
+			options: SerializerOptions);
+
+		response.IsSuccessStatusCode.Should().BeTrue(because: "The test account should exist. If it does not, use the /Account/TestAccount route to create it.");
+
+		var bearerToken = (await response.Content.ReadFromJsonAsync<LoginResponse>())?.AccessToken;
+		this.HttpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", bearerToken);
+
+		response = await this.HttpClient.PostAsJsonAsync(
+			RelativeUri("login"),
+			new
+			{
+				email = "aat-account-2",
+				password = this.testAccountPassword,
+			},
+			options: SerializerOptions);
+
+		response.IsSuccessStatusCode.Should().BeTrue(because: "The test account should exist. If it does not, use the /Account/TestAccount route to create it.");
+
+		bearerToken = (await response.Content.ReadFromJsonAsync<LoginResponse>())?.AccessToken;
+		this.OtherHttpClient.DefaultRequestHeaders.Authorization = new System.Net.Http.Headers.AuthenticationHeaderValue("Bearer", bearerToken);
+	}
+
+	public async Task InitializeAsync()
+	{
+		await this.LoginToTestAccounts();
+	}
+
+	protected virtual void Dispose(bool disposing)
+	{
+		if (!this.disposedValue)
+		{
+			if (disposing)
+			{
+				this.HttpClient.Dispose();
+			}
+
+			this.disposedValue = true;
+		}
+	}
+
+	public Task DisposeAsync()
+	{
+		this.Dispose(true);
+		return Task.CompletedTask;
+	}
+
+	public void Dispose()
+	{
+		this.Dispose(disposing: true);
+		GC.SuppressFinalize(this);
+	}
+
+	protected static Uri RelativeUri(string s) => new(s, UriKind.Relative);
+
+	private class LoginResponse
+	{
+		public string AccessToken { get; set; } = string.Empty;
+	}
+
+}