feat(07-05): create UserAccessAuditView code-behind

- UserControl with UserAccessAuditViewModel constructor injection, sets DataContext
- Wires SearchResults.CollectionChanged to show/hide autocomplete ListBox
- OnSearchResultClicked handler invokes AddUserCommand for mouse-based user selection

SharepointToolbox/Views/Tabs/UserAccessAuditView.xaml.cs

@@ -0,0 +1,41 @@
+using System.Collections.Specialized;
+using System.Windows;
+using System.Windows.Controls;
+using SharepointToolbox.ViewModels.Tabs;
+
+namespace SharepointToolbox.Views.Tabs;
+
+public partial class UserAccessAuditView : UserControl
+{
+    public UserAccessAuditView(UserAccessAuditViewModel viewModel)
+    {
+        InitializeComponent();
+        DataContext = viewModel;
+
+        // Show/hide the autocomplete list as SearchResults changes
+        viewModel.SearchResults.CollectionChanged += OnSearchResultsChanged;
+    }
+
+    private void OnSearchResultsChanged(object? sender, NotifyCollectionChangedEventArgs e)
+    {
+        if (DataContext is UserAccessAuditViewModel vm)
+        {
+            SearchResultsList.Visibility = vm.SearchResults.Count > 0
+                ? Visibility.Visible
+                : Visibility.Collapsed;
+        }
+    }
+
+    /// <summary>
+    /// Handles click on a search result item in the autocomplete list.
+    /// Invokes AddUserCommand on the ViewModel and hides the list.
+    /// </summary>
+    private void OnSearchResultClicked(object sender, System.Windows.Input.MouseButtonEventArgs e)
+    {
+        if (sender is ListBoxItem item && DataContext is UserAccessAuditViewModel vm)
+        {
+            vm.AddUserCommand.Execute(item.DataContext);
+            // AddUserCommand clears SearchResults so CollectionChanged will hide the list
+        }
+    }
+}