Fix type error in ModernGlassButton onPressed: provide always non-null callback with permission check inside

b0esche_cloud/lib/widgets/organization_settings_dialog.dart

@@ -517,15 +517,28 @@ class _OrganizationSettingsDialogState
         ),
         const SizedBox(height: 16),
         ModernGlassButton(
-          onPressed: _canManage ? () {
-            final username = usernameController.text.trim();
-            if (username.isNotEmpty) {
-              _inviteUser(username, selectedRole);
-              usernameController.clear();
+          onPressed: () {
+            if (_canManage) {
+              final username = usernameController.text.trim();
+              if (username.isNotEmpty) {
+                _inviteUser(username, selectedRole);
+                usernameController.clear();
+              }
+            } else {
+              ScaffoldMessenger.of(context).showSnackBar(
+                const SnackBar(
+                  content: Text(
+                    'You do not have permission to send invitations',
+                  ),
+                ),
+              );
             }
-          } : null,
+          },
           child: const Text('Send Invitation'),
         ),
+
+        // Invite link section
+        if (_inviteLink != null) ...[
           const Divider(),
           Text(
             'Invite Link',