Refactor Send Invitation button to use fixed width for better layout consistency

b0esche_cloud/lib/widgets/organization_settings_dialog.dart

@@ -584,7 +584,9 @@ class _OrganizationSettingsDialogState
           ),
         ),
         const SizedBox(height: 16),
-        ModernGlassButton(
+        SizedBox(
+          width: 120,
+          child: ModernGlassButton(
             onPressed: () {
               if (_canManage) {
                 final username = usernameController.text.trim();
@@ -604,6 +606,7 @@ class _OrganizationSettingsDialogState
             },
             child: const Text('Send Invitation'),
           ),
+        ),
       ],
     );
   }