feat(07-07): add DI registrations for Phase 7 services and create UserAccessAuditView

- Register IUserAccessAuditService, IGraphUserSearchService, export services, ViewModel and View in App.xaml.cs
- Create UserAccessAuditView.xaml with two-panel layout: people picker, site picker, scan options, color-coded DataGrid with grouping, summary banner
- Create UserAccessAuditView.xaml.cs code-behind with ViewModel constructor injection
- [Rule 3] UserAccessAuditView was missing (07-05 not executed); created inline to unblock 07-07

SharepointToolbox/Views/Tabs/UserAccessAuditView.xaml.cs

@@ -1,5 +1,3 @@
-using System.Collections.Specialized;
-using System.Windows;
 using System.Windows.Controls;
 using SharepointToolbox.ViewModels.Tabs;
 
@@ -11,31 +9,5 @@ public partial class UserAccessAuditView : UserControl
     {
         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
-        }
     }
 }