feat(17-02): wire ISharePointGroupResolver into PermissionsViewModel export flow

- Add _groupResolver field (ISharePointGroupResolver?) with constructor injection
- ISharePointGroupResolver added as optional last parameter in main constructor
- ExportHtmlAsync resolves SharePoint group names before calling WriteAsync
- Gracefully handles resolution failure with LogWarning, exports without expansion
- Both WriteAsync call sites pass groupMembers dict (standard and simplified paths)

SharepointToolbox/ViewModels/Tabs/PermissionsViewModel.cs

@@ -27,6 +27,7 @@ public partial class PermissionsViewModel : FeatureViewModelBase
     private readonly CsvExportService? _csvExportService;
     private readonly HtmlExportService? _htmlExportService;
     private readonly IBrandingService? _brandingService;
+    private readonly ISharePointGroupResolver? _groupResolver;
     private readonly ILogger<FeatureViewModelBase> _logger;
 
     // ── Observable properties ───────────────────────────────────────────────
@@ -134,7 +135,8 @@ public partial class PermissionsViewModel : FeatureViewModelBase
         CsvExportService csvExportService,
         HtmlExportService htmlExportService,
         IBrandingService brandingService,
-        ILogger<FeatureViewModelBase> logger)
+        ILogger<FeatureViewModelBase> logger,
+        ISharePointGroupResolver? groupResolver = null)
         : base(logger)
     {
         _permissionsService = permissionsService;
@@ -143,6 +145,7 @@ public partial class PermissionsViewModel : FeatureViewModelBase
         _csvExportService = csvExportService;
         _htmlExportService = htmlExportService;
         _brandingService = brandingService;
+        _groupResolver = groupResolver;
         _logger = logger;
 
         ExportCsvCommand = new AsyncRelayCommand(ExportCsvAsync, CanExport);
@@ -330,10 +333,37 @@ public partial class PermissionsViewModel : FeatureViewModelBase
                 branding = new ReportBranding(mspLogo, clientLogo);
             }
 
+            IReadOnlyDictionary<string, IReadOnlyList<ResolvedMember>>? groupMembers = null;
+            if (_groupResolver != null && Results.Count > 0)
+            {
+                var groupNames = Results
+                    .Where(r => r.PrincipalType == "SharePointGroup")
+                    .SelectMany(r => r.Users.Split(';', StringSplitOptions.RemoveEmptyEntries))
+                    .Select(n => n.Trim())
+                    .Where(n => n.Length > 0)
+                    .Distinct(StringComparer.OrdinalIgnoreCase)
+                    .ToList();
+
+                if (groupNames.Count > 0 && _currentProfile != null)
+                {
+                    try
+                    {
+                        var ctx = await _sessionManager.GetOrCreateContextAsync(
+                            _currentProfile, CancellationToken.None);
+                        groupMembers = await _groupResolver.ResolveGroupsAsync(
+                            ctx, _currentProfile.ClientId, groupNames, CancellationToken.None);
+                    }
+                    catch (Exception ex)
+                    {
+                        _logger.LogWarning(ex, "Group resolution failed — exporting without member expansion.");
+                    }
+                }
+            }
+
             if (IsSimplifiedMode && SimplifiedResults.Count > 0)
-                await _htmlExportService.WriteAsync(SimplifiedResults.ToList(), dialog.FileName, CancellationToken.None, branding);
+                await _htmlExportService.WriteAsync(SimplifiedResults.ToList(), dialog.FileName, CancellationToken.None, branding, groupMembers);
             else
-                await _htmlExportService.WriteAsync(Results, dialog.FileName, CancellationToken.None, branding);
+                await _htmlExportService.WriteAsync(Results, dialog.FileName, CancellationToken.None, branding, groupMembers);
             OpenFile(dialog.FileName);
         }
         catch (Exception ex)