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.Application/Envelopes/Queries/ReadEnvelopeQuery.cs

@@ -14,6 +14,16 @@ namespace EnvelopeGenerator.Application.Envelopes.Queries;
 /// </summary>
 public record ReadEnvelopeQuery : EnvelopeQueryBase, IRequest<IEnumerable<EnvelopeDto>>
 {
+    /// <summary>
+    /// 
+    /// </summary>
+    public bool OnlyActive { get; init; } = false;
+
+    /// <summary>
+    /// 
+    /// </summary>
+    public bool OnlyCompleted { get; init; } = false;
+
     /// <summary>
     /// Abfrage des Include des Umschlags
     /// </summary>
@@ -132,6 +142,12 @@ public class ReadEnvelopeQueryHandler : IRequestHandler<ReadEnvelopeQuery, IEnum
                 query = query.Where(e => !status.Ignore.Contains(e.Status));
         }
 
+        if(request is { OnlyActive: true })
+            query = query.Where(e => Status.Active.Contains(e.Status));
+
+        if (request is { OnlyCompleted: true })
+            query = query.Where(e => Status.Completed.Contains(e.Status));
+
         var envelopes = await query
             .Include(e => e.EnvelopeReceivers).ThenInclude(er => er.Receiver)
             .ToListAsync(cancel);