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/Identity/IAccountManagement.cs

@@ -0,0 +1,31 @@
+namespace Shogi.UI.Identity;
+
+/// <summary>
+/// Account management services.
+/// </summary>
+public interface IAccountManagement
+{
+	/// <summary>
+	/// Login service.
+	/// </summary>
+	/// <param name="email">User's email.</param>
+	/// <param name="password">User's password.</param>
+	/// <returns>The result of the request serialized to <see cref="FormResult"/>.</returns>
+	public Task<FormResult> LoginAsync(string email, string password);
+
+	/// <summary>
+	/// Log out the logged in user.
+	/// </summary>
+	/// <returns>The asynchronous task.</returns>
+	public Task LogoutAsync();
+
+	/// <summary>
+	/// Registration service.
+	/// </summary>
+	/// <param name="email">User's email.</param>
+	/// <param name="password">User's password.</param>
+	/// <returns>The result of the request serialized to <see cref="FormResult"/>.</returns>
+	public Task<FormResult> RegisterAsync(string email, string password);
+
+	public Task<bool> CheckAuthenticatedAsync();
+}