docs: add XML documentation to NEW solution src files

Fix 173 of 175 documentation issues across 48 files using CommentChecker,
adding missing <summary>, <param>, and <inheritdoc /> tags to public APIs.

NEW/src/Utils/JdeScoping.ConfigManager/ViewModels/MainWindowViewModel.cs

@@ -194,6 +194,7 @@ public class MainWindowViewModel : ViewModelBase
     /// <param name="secureStoreManager">Service for managing encrypted secret stores.</param>
     /// <param name="clipboardService">Service for clipboard operations.</param>
     /// <param name="runtimeValidationService">Service for runtime configuration validation.</param>
+    /// <param name="connectionTestService">Service for testing database connections.</param>
     /// <param name="logger">Optional logger for recording view model activities.</param>
     public MainWindowViewModel(
         IFileSystem fileSystem,
@@ -271,6 +272,11 @@ public class MainWindowViewModel : ViewModelBase
     /// </summary>
     private class NullClipboardService : IClipboardService
     {
+        /// <summary>
+        /// Sets text to clipboard (no-op for design-time).
+        /// </summary>
+        /// <param name="text">The text to set (ignored in this implementation).</param>
+        /// <returns>A completed task.</returns>
         public Task SetTextAsync(string text) => Task.CompletedTask;
     }