Refactor: Revert to hard deletes for messages. Remove IsDeleted flag and update repository and configurations accordingly.

Govor.Contracts/Responses/SignalR/MessageRemovedResponse.cs

@@ -0,0 +1,11 @@
+using Govor.Core.Models; // For RecipientType
+
+namespace Govor.Contracts.Responses.SignalR;
+
+public class MessageRemovedResponse
+{
+    public Guid MessageId { get; set; }
+    public Guid SenderId { get; set; } // Original Sender
+    public Guid RecipientId { get; set; }
+    public RecipientType RecipientType { get; set; }
+}