fix(admin): corregir guardado customcssmanager con toast

- crear bootstrap para handler post en admin_init
- ocultar botones globales para custom-css-manager
- simplificar formbuilder eliminando handler duplicado
- reemplazar alert por toast para notificaciones

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Admin/Infrastructure/Ui/Views/partials/component-view.php

@@ -60,6 +60,12 @@ $group = $groupId && isset($groups[$groupId]) ? $groups[$groupId] : null;
         </div>
     </div>
 
+    <?php
+    // Componentes con sistema de guardado propio (CRUD de entidades)
+    $componentsWithOwnSaveSystem = ['custom-css-manager'];
+
+    if (!in_array($activeComponent, $componentsWithOwnSaveSystem, true)):
+    ?>
     <!-- Botones Globales Save/Cancel -->
     <div class="d-flex justify-content-end gap-2 p-3 rounded border mt-4" style="background-color: #f8f9fa; border-color: #e9ecef !important;">
         <button type="button" class="btn btn-outline-secondary" id="cancelChanges">
@@ -71,4 +77,5 @@ $group = $groupId && isset($groups[$groupId]) ? $groups[$groupId] : null;
             <?php echo esc_html__('Guardar Cambios', 'roi-theme'); ?>
         </button>
     </div>
+    <?php endif; ?>
 </div>