feat(configmanager): integrate SecureStore for credential management

Add SecureStore integration to ConfigManager for secure handling of connection
strings and sensitive configuration values. Includes store/secret management
UI, encrypted .store file support, and comprehensive test coverage.

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

@@ -1,5 +1,6 @@
 using JdeScoping.ConfigManager.Models;
 using JdeScoping.ConfigManager.Services;
+using JdeScoping.ConfigManager.Services.SecureStore;
 using JdeScoping.ConfigManager.ViewModels;
 using JdeScoping.ConfigManager.ViewModels.Forms;
 using Microsoft.Extensions.Logging;
@@ -15,6 +16,8 @@ public class MainWindowViewModelTests
     private readonly IBackupService _backupService;
     private readonly IAutoDiscoveryService _autoDiscoveryService;
     private readonly IDialogService _dialogService;
+    private readonly ISecureStoreManager _secureStoreManager;
+    private readonly IClipboardService _clipboardService;
     private readonly ILogger<MainWindowViewModel> _logger;
 
     public MainWindowViewModelTests()
@@ -25,6 +28,8 @@ public class MainWindowViewModelTests
         _backupService = Substitute.For<IBackupService>();
         _autoDiscoveryService = Substitute.For<IAutoDiscoveryService>();
         _dialogService = Substitute.For<IDialogService>();
+        _secureStoreManager = Substitute.For<ISecureStoreManager>();
+        _clipboardService = Substitute.For<IClipboardService>();
         _logger = Substitute.For<ILogger<MainWindowViewModel>>();
 
         _validationService.ValidateAppSettings(Arg.Any<ConfigModel>())
@@ -274,7 +279,7 @@ public class MainWindowViewModelTests
         sut.LoadConfigForTesting(config, null);
 
         // Assert
-        sut.TreeNodes.Count.ShouldBe(2); // Settings and Pipelines folders
+        sut.TreeNodes.Count.ShouldBe(3); // Settings, Pipelines, and Secure Stores folders
         sut.TreeNodes[0].Name.ShouldBe("Settings");
         sut.TreeNodes[0].Children.Count.ShouldBe(6); // DataSync, DataAccess, Auth, Ldap, Search, ExcelExport
     }
@@ -311,6 +316,8 @@ public class MainWindowViewModelTests
             _backupService,
             _autoDiscoveryService,
             _dialogService,
+            _secureStoreManager,
+            _clipboardService,
             _logger);
     }
 }