fixed some bugs, added ability to work without internet

Mlaumcherb.Client.Avalonia/сеть/NetworkHelper.cs

@@ -12,6 +12,7 @@ public static class NetworkHelper
         // thanks for Sashok :3
         // https://github.com/new-sashok724/Launcher/blob/23485c3f7de6620d2c6b7b2dd9339c3beb6a0366/Launcher/source/helper/IOHelper.java#L259
         _http.DefaultRequestHeaders.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)");
+        _http.Timeout = TimeSpan.FromSeconds(4);
     }
 
     public static Task<string> GetString(string url, CancellationToken ct = default) => _http.GetStringAsync(url, ct);