Add envelope history tracking and receiver signing status

Added a `Histories` property to `EnvelopeDto` to track envelope
history entries for actions like `DocumentSigned` and
`EnvelopeOpened`. Introduced a computed `Signed` property in
`EnvelopeReceiverDto` to determine if a receiver has signed the
envelope based on the history. Updated `using` directives to
support these changes.

EnvelopeGenerator.Application/Common/Dto/EnvelopeReceiver/EnvelopeReceiverDto.cs

@@ -1,5 +1,6 @@
 using DigitalData.EmailProfilerDispatcher.Abstraction.Attributes;
 using EnvelopeGenerator.Application.Common.Dto.Receiver;
+using EnvelopeGenerator.Domain.Constants;
 
 namespace EnvelopeGenerator.Application.Common.Dto.EnvelopeReceiver;
 
@@ -73,4 +74,13 @@ public record EnvelopeReceiverDto
     /// 
     /// </summary>
     public bool HasPhoneNumber { get; init; }
+
+    /// <summary>
+    /// Indicates whether this receiver has signed the envelope.
+    /// Checks if there is a DocumentSigned history entry for this receiver in the envelope's history.
+    /// </summary>
+    public bool Signed => Envelope?.Histories?.Any(h => 
+        h.Receiver?.Id == ReceiverId && 
+        h.Status == EnvelopeStatus.DocumentSigned
+    ) ?? false;
 }