added singleUserMode and removed StaffSection from forms

lib/core/widgets/staff_selector_modal.dart

@@ -79,7 +79,10 @@ class StaffSelectorModal extends StatelessWidget {
     );
   }
 
-  Widget _buildStaffGrid(BuildContext context, List<dynamic> staffList) {
+  Widget _buildStaffGrid(
+    BuildContext context,
+    List<StaffMemberModel> staffList,
+  ) {
     return Wrap(
       spacing: 16,
       runSpacing: 16,
@@ -98,7 +101,7 @@ class StaffSelectorModal extends StatelessWidget {
             decoration: BoxDecoration(
               color: Theme.of(
                 context,
-              ).colorScheme.surfaceContainerHighest.withOpacity(0.3),
+              ).colorScheme.surfaceContainerHighest.withValues(alpha: 0.3),
               borderRadius: BorderRadius.circular(16),
               border: Border.all(color: Theme.of(context).dividerColor),
             ),
@@ -109,7 +112,7 @@ class StaffSelectorModal extends StatelessWidget {
                   backgroundColor: Theme.of(context).colorScheme.primary,
                   foregroundColor: Theme.of(context).colorScheme.onPrimary,
                   child: Text(
-                    staff['name'].substring(0, 1).toUpperCase(),
+                    staff.name.substring(0, 1).toUpperCase(),
                     style: const TextStyle(
                       fontSize: 24,
                       fontWeight: FontWeight.bold,
@@ -118,7 +121,7 @@ class StaffSelectorModal extends StatelessWidget {
                 ),
                 const SizedBox(height: 12),
                 Text(
-                  staff['name'],
+                  staff.name,
                   style: const TextStyle(fontWeight: FontWeight.bold),
                   overflow: TextOverflow.ellipsis,
                 ),