Move LayoutDto to its own file and update namespace

Separated LayoutDto from LayoutsController.cs into LayoutDto.cs and set its namespace to DbFirst.Application.Layouts for better code organization and maintainability.

DbFirst.API/Controllers/LayoutsController.cs

@@ -2,6 +2,7 @@ using System.Text;
 using DbFirst.Application.Repositories;
 using DbFirst.Domain.Entities;
 using Microsoft.AspNetCore.Mvc;
+using DbFirst.Application.Layouts;
 
 namespace DbFirst.API.Controllers;
 
@@ -83,12 +84,4 @@ public class LayoutsController : ControllerBase
             LayoutData = layoutData
         };
     }
-
-    public sealed class LayoutDto
-    {
-        public string LayoutType { get; set; } = string.Empty;
-        public string LayoutKey { get; set; } = string.Empty;
-        public string UserName { get; set; } = string.Empty;
-        public string LayoutData { get; set; } = string.Empty;
-    }
 }