begin new and last rework

OwnChar.Server/Api/IServer.cs

@@ -0,0 +1,21 @@
+using OwnChar.Data;
+using OwnChar.Model;
+using Pilz.Configuration;
+using System.Diagnostics.CodeAnalysis;
+
+namespace OwnChar.ServerNew.Api;
+
+public interface IServer
+{
+    ISettings Settings { get; }
+    IDataProvider? Data { get; }
+
+    [MemberNotNull(nameof(Data))]
+    void CheckLogin(string secret);
+
+    [MemberNotNullWhen(true, nameof(Data))]
+    bool IsLoggedIn(string secret);
+
+    [MemberNotNullWhen(true, nameof(Data))]
+    UserAccount? GetUser(string secret);
+}