Products megamenu as a data-driven catalog with a Solr product type-ahead

- evo_megamenu_json stays project-neutral: new panel layout "catalog";
  for such entries the MenuBuilder dispatches the new PSR-14 event
  BuildCatalogEvent and emits whatever a listener sets as `catalog`
  (null without a listener). The entry's teaser cards serve as the
  featured tiles; the teaser inline field now also shows for "catalog",
  and the entry form reloads when the layout changes. README section
  "Layout catalog"
- VITEC listener ProvideProductCatalog fills it, modelled on the Ross
  Video products menu: main categories below the "Product" root, their
  subcategories as groups, products with a plain-text one-line teaser;
  same visibility rules as the product list, Product Finder links
  (/products?cat=&subcat=), empty categories and groups left out, three
  queries for the whole catalog
- Product type-ahead GET /_json/?type=7385&q= (USER_INT page type,
  ProductMenuSearchJsonRenderer): Solr restricted to products, last term
  completed as a prefix, up to six product cards plus their titles as
  autocomplete suggestions; endpoint announced in catalog.search
- Spec v1.23 (clause 7.16: product type-ahead)

packages/evo_megamenu_json/Classes/Service/MenuBuilder.php

@@ -5,6 +5,8 @@ declare(strict_types=1);
 namespace Evomedien\EvoMegamenuJson\Service;
 
 use Doctrine\DBAL\ParameterType;
+use Evomedien\EvoMegamenuJson\Event\BuildCatalogEvent;
+use Psr\EventDispatcher\EventDispatcherInterface;
 use TYPO3\CMS\Core\Database\ConnectionPool;
 use TYPO3\CMS\Core\Database\Query\QueryBuilder;
 use TYPO3\CMS\Core\Database\Query\Restriction\FrontendRestrictionContainer;
@@ -52,6 +54,7 @@ final class MenuBuilder
         private readonly FlexFormService $flexFormService,
         private readonly PageRepository $pageRepository,
         private readonly FileRepository $fileRepository,
+        private readonly EventDispatcherInterface $eventDispatcher,
     ) {}
 
     /**
@@ -82,7 +85,10 @@ final class MenuBuilder
      */
     private function buildEntry(array $entry, int $stage, ContentObjectRenderer $cObj): array
     {
-        $layout = (string)($entry['layout'] ?? 'columns') === 'teasers' ? 'teasers' : 'columns';
+        $layout = (string)($entry['layout'] ?? 'columns');
+        if (!in_array($layout, ['columns', 'teasers', 'catalog'], true)) {
+            $layout = 'columns';
+        }
 
         $columns = [];
         foreach ($this->children(self::TABLE_COLUMN, (int)$entry['uid']) as $column) {
@@ -104,7 +110,15 @@ final class MenuBuilder
             'columns' => $columns,
         ];
 
-        if ($layout === 'teasers') {
+        // Catalog panels: the teaser cards serve as the featured tiles (left
+        // column), the catalog data itself comes from a listener of
+        // BuildCatalogEvent - this extension does not know the data source.
+        if ($layout === 'catalog') {
+            $event = $this->eventDispatcher->dispatch(new BuildCatalogEvent($entry, $stage));
+            $built['catalog'] = $event->getCatalog();
+        }
+
+        if ($layout === 'teasers' || $layout === 'catalog') {
             $teasers = [];
             foreach ($this->children(self::TABLE_TEASER, (int)$entry['uid']) as $teaser) {
                 $card = [