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/UserInfo.cs

@@ -0,0 +1,22 @@
+namespace Shogi.UI.Identity;
+
+/// <summary>
+/// User info from identity endpoint to establish claims.
+/// </summary>
+public class UserInfo
+{
+	/// <summary>
+	/// The email address.
+	/// </summary>
+	public string Email { get; set; } = string.Empty;
+
+	/// <summary>
+	/// A value indicating whether the email has been confirmed yet.
+	/// </summary>
+	public bool IsEmailConfirmed { get; set; }
+
+	/// <summary>
+	/// The list of claims for the user.
+	/// </summary>
+	public Dictionary<string, string> Claims { get; set; } = [];
+}