feat(configmanager): add ConnectionStrings editor with test connection support

Adds a new ConnectionStrings section to ConfigManager allowing users to manage
database connection strings with provider selection, connection testing, and
visual feedback for connection state.

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

@@ -19,6 +19,7 @@ public class MainWindowViewModelTests
     private readonly ISecureStoreManager _secureStoreManager;
     private readonly IClipboardService _clipboardService;
     private readonly IRuntimeConfigValidationService _runtimeValidationService;
+    private readonly IConnectionTestService _connectionTestService;
     private readonly ILogger<MainWindowViewModel> _logger;
 
     public MainWindowViewModelTests()
@@ -32,6 +33,7 @@ public class MainWindowViewModelTests
         _secureStoreManager = Substitute.For<ISecureStoreManager>();
         _clipboardService = Substitute.For<IClipboardService>();
         _runtimeValidationService = Substitute.For<IRuntimeConfigValidationService>();
+        _connectionTestService = Substitute.For<IConnectionTestService>();
         _logger = Substitute.For<ILogger<MainWindowViewModel>>();
 
         _validationService.ValidateAppSettings(Arg.Any<ConfigModel>())
@@ -284,7 +286,7 @@ public class MainWindowViewModelTests
         // Without a configured/open SecureStore, only Settings and Pipelines appear
         sut.TreeNodes.Count.ShouldBe(2); // Settings, Pipelines (no Secure Store when not configured)
         sut.TreeNodes[0].Name.ShouldBe("Settings");
-        sut.TreeNodes[0].Children.Count.ShouldBe(6); // DataSync, DataAccess, Auth, Ldap, Search, ExcelExport
+        sut.TreeNodes[0].Children.Count.ShouldBe(7); // ConnectionStrings, DataSync, DataAccess, Auth, Ldap, Search, ExcelExport
         sut.TreeNodes[1].Name.ShouldBe("Pipelines");
     }
 
@@ -382,6 +384,7 @@ public class MainWindowViewModelTests
             _secureStoreManager,
             _clipboardService,
             _runtimeValidationService,
+            _connectionTestService,
             _logger);
     }
 }