add server status & capabilities

Pilz.Net/Api/Messages/ServerStatusMessage.cs

@@ -0,0 +1,10 @@
+namespace Pilz.Net.Api.Messages;
+
+public class ServerStatusMessage : ApiMessage
+{
+    public AppVersion? AppVersion { get; set; }
+    public uint ApiVersion { get; set; }
+    public int EndpointsCount { get; set; }
+    public int DataManagersCount { get; set; }
+    public uint RestartAttempts { get; set; }
+}