Add EventParticipant DTOs

BusinessLayer/DTOs/EventParticipant/EventParticipantCreateDTO.cs

+using DAL.Enums;
+using System.ComponentModel.DataAnnotations;
+
+namespace BusinessLayer.DTOs.EventParticipant
+{
+    public class EventParticipantCreateDTO
+    {
+        [Required]
+        public Guid UserId { get; set; }
+
+        [Required]
+        public Guid EventId { get; set; }
+
+        [Required]
+        public ParticipantType Attendance { get; set; }
+    }
+}

BusinessLayer/DTOs/EventParticipant/EventParticipantDTO.cs

+using BusinessLayer.DTOs.Event;
+using BusinessLayer.DTOs.User;
+using DAL.Enums;
+
+namespace BusinessLayer.DTOs.EventParticipant
+{
+    public class EventParticipantDTO
+    {
+        public Guid Id { get; set; }
+        public required UserDTO User { get; set; }
+        public required EventDTO Event { get; set; }
+        public ParticipantType Attendance { get; set; }
+        public DateTime CreatedAt { get; set; }
+        public DateTime UpdatedAt { get; set; }
+        public DateTime? DeletedAt { get; set; }
+    }
+}

BusinessLayer/DTOs/EventParticipant/EventParticipantUpdateDTO.cs

+using DAL.Enums;
+using System.ComponentModel.DataAnnotations;
+
+namespace BusinessLayer.DTOs.EventParticipant
+{
+    public class EventParticipantUpdateDTO
+    {
+        [Required]
+        public ParticipantType Attendance { get; set; }
+    }
+}
\ No newline at end of file