Unify list plugins, add solution list and per-story detail page

- vitec_usecaselist: layout + record selection like marketlist
- new plugin vitec_solutionlist (spec 7.13.3, key "solutions")
- tx_vitec_domain_model_usecase: detail_page -> resolved detailUrl
  (also gives story cards in vitec_modelcard a link for the first time)
- "Show Toolbar" checkbox on product/market/solution/usecase lists
- spec bumped to v1.9

BREAKING: vitec_productlist and vitec_usecaselist now emit an object
instead of a bare array. Consumers must read products.products and
usecases.usecases. Also found: productlist had a configurable layout
that was never serialised; it is emitted now, but keeps its own 0-3
vocabulary instead of grid/list/carousel.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

packages/vitec/Classes/Domain/Model/Usecase.php

@@ -19,6 +19,14 @@ class Usecase extends AbstractEntity
      */
     protected $slug = '';
 
+    /**
+     * Page that presents this story. 0 = none; the list plugin then falls back
+     * to its own "Single PID" detail page plus the slug.
+     *
+     * @var int
+     */
+    protected $detailPage = 0;
+
     /**
      * subtitle
      *
@@ -110,6 +118,16 @@ class Usecase extends AbstractEntity
         return $this->slug;
     }
 
+    public function getDetailPage(): int
+    {
+        return $this->detailPage;
+    }
+
+    public function setDetailPage(int $detailPage): void
+    {
+        $this->detailPage = $detailPage;
+    }
+
     /**
      * @param string $slug
      */