add check context events

Pilz.Net/Api/ApiServer.cs

@@ -13,6 +13,8 @@ public class ApiServer(string apiUrl) : IApiServer
     protected readonly HttpListener httpListener = new();
 
     public event OnCheckAuthenticationEventHandler? OnCheckAuthentication;
+    public event OnCheckContextEventHandler? OnCheckContext;
+    public event OnCheckContextEventHandler? OnCheckContextCompleted;
 
     protected record PrivateApiResult(ApiResult Original, string? ResultJson);
 
@@ -104,6 +106,7 @@ public class ApiServer(string apiUrl) : IApiServer
             Receive();
 
         // Check context
+        OnCheckContext?.Invoke(this, new(context));
         try
         {
             CheckContext(context);
@@ -114,6 +117,10 @@ public class ApiServer(string apiUrl) : IApiServer
             if (DebugMode)
                 throw;
         }
+        finally
+        {
+            OnCheckContextCompleted?.Invoke(this, new(context));
+        }
 
         // Listen for new request
         if (!AllowMultipleRequests)