Enhanced material design 3 implementation

lib/screens/admin/user_management_screen.dart

@@ -14,6 +14,8 @@ import '../../theme/app_surfaces.dart';
 import '../../providers/user_offices_provider.dart';
 
 import '../../utils/app_time.dart';
+import '../../widgets/app_page_header.dart';
+import '../../widgets/app_state_view.dart';
 import '../../widgets/mono_text.dart';
 import '../../widgets/responsive_body.dart';
 import '../../widgets/tasq_adaptive_list.dart';
@@ -105,7 +107,14 @@ class _UserManagementScreenState extends ConsumerState<UserManagementScreen> {
           assignmentsAsync.error ??
           messagesAsync.error ??
           'Unknown error';
-      return Center(child: Text('Failed to load data: $error'));
+      return AppErrorView(
+        error: error,
+        onRetry: () {
+          ref.invalidate(profilesProvider);
+          ref.invalidate(officesProvider);
+          ref.invalidate(userOfficesProvider);
+        },
+      );
     }
 
     final profiles = profilesAsync.valueOrNull ?? [];
@@ -124,7 +133,11 @@ class _UserManagementScreenState extends ConsumerState<UserManagementScreen> {
     }
 
     if (profiles.isEmpty) {
-      return const Center(child: Text('No users found.'));
+      return const AppEmptyView(
+        icon: Icons.people_outline,
+        title: 'No users found',
+        subtitle: 'Users who sign up will appear here.',
+      );
     }
 
     final query = _searchController.text.trim().toLowerCase();
@@ -269,26 +282,16 @@ class _UserManagementScreenState extends ConsumerState<UserManagementScreen> {
       isLoading: false,
     );
 
-    return Padding(
-      padding: const EdgeInsets.symmetric(vertical: 16),
-      child: Column(
-        mainAxisSize: MainAxisSize.max,
-        crossAxisAlignment: CrossAxisAlignment.stretch,
-        children: [
-          Align(
-            alignment: Alignment.center,
-            child: Text(
-              'User Management',
-              textAlign: TextAlign.center,
-              style: Theme.of(
-                context,
-              ).textTheme.titleLarge?.copyWith(fontWeight: FontWeight.w700),
-            ),
-          ),
-          const SizedBox(height: 16),
-          Expanded(child: listBody),
-        ],
-      ),
+    return Column(
+      mainAxisSize: MainAxisSize.max,
+      crossAxisAlignment: CrossAxisAlignment.stretch,
+      children: [
+        const AppPageHeader(
+          title: 'User Management',
+          subtitle: 'Manage user roles and office assignments',
+        ),
+        Expanded(child: listBody),
+      ],
     );
   }