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/CookieMessageHandler.cs

@@ -0,0 +1,14 @@
+using Microsoft.AspNetCore.Components.WebAssembly.Http;
+
+namespace Shogi.UI.Identity;
+
+public class CookieCredentialsMessageHandler : DelegatingHandler
+{
+    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+    {
+        request.SetBrowserRequestCredentials(BrowserRequestCredentials.Include);
+        request.Headers.Add("X-Requested-With", ["XMLHttpRequest"]);
+
+        return base.SendAsync(request, cancellationToken);
+    }
+}