Add filtering for active and completed envelopes

Added `OnlyActive` and `OnlyCompleted` properties to the `ReadEnvelopeQuery` class to enable filtering envelopes by their active or completed status. Updated the `ReadEnvelopeQueryHandler` to apply these filters when the properties are set.

Enhanced the `EnvelopeStatus` class by introducing `Active` and `Completed` status lists and adding extension methods (`IsActive` and `IsCompleted`) to determine status categories. Included necessary `using` directives for `System` and `System.Linq`.

EnvelopeGenerator.Domain/Constants/EnvelopeStatus.cs

@@ -1,8 +1,10 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace EnvelopeGenerator.Domain.Constants
 {
-    // http://wiki.dd/xwiki13/bin/view/Anwendungen/Produkt-Handbuch/Sonstiges/SignFlow/Envelope%20Status/
+    // http://wiki.dd/xwiki_prod/bin/view/Anwendungen/Produkt-Handbuch/Sonstiges/signFLOW/signFLOW%20-%20Enwickler-Handbuch/4.%20Anhang/4.3%20Historie%20und%20Status%20der%20Umschl%C3%A4ge/
     public enum EnvelopeStatus
     {
         Invalid = 0,
@@ -49,5 +51,28 @@ namespace EnvelopeGenerator.Domain.Constants
                 EnvelopeStatus.EnvelopeCreated,
                 EnvelopeStatus.DocumentMod_Rotation
             };
+
+        public static readonly List<EnvelopeStatus> Active = Enum.GetValues(typeof(EnvelopeStatus))
+            .Cast<EnvelopeStatus>()
+            .Where(status => status.IsActive())
+            .ToList();
+
+        public static readonly List<EnvelopeStatus> Completed = Enum.GetValues(typeof(EnvelopeStatus))
+            .Cast<EnvelopeStatus>()
+            .Where(status => status.IsCompleted())
+            .ToList();
+    }
+
+    public static class EnvelopeStatusExtensions
+    {
+        public static bool IsActive(this EnvelopeStatus status)
+        {
+            return status >= EnvelopeStatus.EnvelopeCreated && status < EnvelopeStatus.EnvelopePartlySigned;
+        }
+
+        public static bool IsCompleted(this EnvelopeStatus status)
+        {
+            return status >= EnvelopeStatus.EnvelopeCompletelySigned && status <= EnvelopeStatus.EnvelopeWithdrawn;
+        }
     }
 }