refactor(core): reorganize DTOs into Models and ViewModels folders

Move DTOs from ApiContracts to appropriate locations:
- SignalR DTOs → ViewModels (renamed Dto→ViewModel suffix)
- Pipeline DTOs → Models/Pipelines
- UserInfoDto → Models/Auth
- DataUpdateDto → Models/Infrastructure

NEW/tests/JdeScoping.Api.Tests/Controllers/AuthControllerTests.cs

@@ -4,7 +4,6 @@ using System.Security.Cryptography;
 using System.Text;
 using System.Text.Json;
 using JdeScoping.Api.Controllers;
-using JdeScoping.Core.ApiContracts.Auth;
 using JdeScoping.Core.Interfaces;
 using JdeScoping.Core.Models;
 using JdeScoping.Core.Models.Auth;

NEW/tests/JdeScoping.Api.Tests/Hubs/StatusHubTests.cs

@@ -1,5 +1,5 @@
 using JdeScoping.Api.Hubs;
-using JdeScoping.Core.ApiContracts.SignalR;
+using JdeScoping.Core.ViewModels;
 using Microsoft.AspNetCore.SignalR;
 using Microsoft.Extensions.Logging;
 using NSubstitute;
@@ -33,7 +33,7 @@ public class StatusHubTests
         var clientsProperty = typeof(Hub).GetProperty("Clients");
         clientsProperty?.SetValue(_hub, hubClients);
 
-        var statusUpdate = new StatusUpdateDto
+        var statusUpdate = new StatusUpdateViewModel
         {
             Message = "Processing",
             Timestamp = DateTime.UtcNow
@@ -90,7 +90,7 @@ public class StatusHubTests
         var clientsProperty = typeof(Hub).GetProperty("Clients");
         clientsProperty?.SetValue(_hub, hubClients);
 
-        var searchUpdate = new SearchUpdateDto
+        var searchUpdate = new SearchUpdateViewModel
         {
             Id = 42,
             UserName = "testuser",

NEW/tests/JdeScoping.Client.Tests/Services/AuthApiClientTests.cs

@@ -2,7 +2,6 @@ using System.Net;
 using System.Text.Json;
 using JdeScoping.Client.Services;
 using JdeScoping.Core.ApiContracts;
-using JdeScoping.Core.ApiContracts.Auth;
 using JdeScoping.Core.ApiContracts.Results;
 using JdeScoping.Core.Models.Auth;
 using RichardSzalay.MockHttp;