Replace calendar service with new .NET version

Calendar/Service/Models/Duration.cs

@@ -0,0 +1,19 @@
+namespace ChrisKaczor.HomeMonitor.Calendar.Service.Models;
+
+public class Duration
+{
+    public int Days { get; set; }
+    public int Hours { get; set; }
+    public int Minutes { get; set; }
+    public int Seconds { get; set; }
+
+    public Duration(DateTimeOffset date)
+    {
+        var now = DateTimeOffset.Now;
+        var duration = date - now;
+        Days = duration.Days;
+        Hours = duration.Hours;
+        Minutes = duration.Minutes;
+        Seconds = duration.Seconds;
+    }
+}