refactor(configmanager): migrate to per-file pipeline system

Align ConfigManager with DataSync's per-file pipeline format (pipeline.*.json)
by reusing EtlPipelineConfig types directly, eliminating duplicate models and
simplifying the codebase. Removes ~3200 lines of obsolete code.

NEW/tests/JdeScoping.ConfigManager.Tests/ViewModels/MainWindowViewModelTests.cs

@@ -3,6 +3,7 @@ using JdeScoping.ConfigManager.Services;
 using JdeScoping.ConfigManager.Services.SecureStore;
 using JdeScoping.ConfigManager.ViewModels;
 using JdeScoping.ConfigManager.ViewModels.Forms;
+using JdeScoping.DataSync.Configuration;
 using Microsoft.Extensions.Logging;
 using NSubstitute;
 
@@ -38,7 +39,7 @@ public class MainWindowViewModelTests
 
         _validationService.ValidateAppSettings(Arg.Any<ConfigModel>())
             .Returns(new ValidationResult());
-        _validationService.ValidatePipelines(Arg.Any<PipelinesConfigModel>())
+        _validationService.ValidatePipelines(Arg.Any<Dictionary<string, EtlPipelineConfig>>())
             .Returns(new ValidationResult());
     }
 
@@ -167,15 +168,13 @@ public class MainWindowViewModelTests
     {
         // Arrange
         var config = new ConfigModel();
-        var pipelines = new PipelinesConfigModel
+        var pipelines = new Dictionary<string, EtlPipelineConfig>
         {
-            Pipelines = new Dictionary<string, PipelineModel>
+            ["WorkOrders"] = new EtlPipelineConfig
             {
-                ["WorkOrders"] = new PipelineModel
-                {
-                    Source = new PipelineSource { Connection = "jde", Query = "SELECT * FROM WO" },
-                    Destination = new PipelineDestination { Table = "WorkOrder_Curr" }
-                }
+                Name = "WorkOrders",
+                Source = new SourceElement { Connection = "jde", Query = "SELECT * FROM WO" },
+                Destination = new DestinationElement { Table = "WorkOrder_Curr" }
             }
         };
         var sut = CreateViewModel();
@@ -295,13 +294,10 @@ public class MainWindowViewModelTests
     {
         // Arrange
         var config = new ConfigModel();
-        var pipelines = new PipelinesConfigModel
+        var pipelines = new Dictionary<string, EtlPipelineConfig>
         {
-            Pipelines = new Dictionary<string, PipelineModel>
-            {
-                ["Pipeline1"] = new PipelineModel(),
-                ["Pipeline2"] = new PipelineModel()
-            }
+            ["Pipeline1"] = new EtlPipelineConfig { Name = "Pipeline1" },
+            ["Pipeline2"] = new EtlPipelineConfig { Name = "Pipeline2" }
         };
         var sut = CreateViewModel();