feat: add product catalogue and product-aware UI

- introduce product catalogue pages, management view entries and shared product composables\n- wire product selection into component/piece flows and machine skeleton requirements\n- display linked product metadata and documents across machine, component and piece views\n- generalize model type tooling to handle PRODUCT category

app/pages/machine-skeleton/index.vue

@@ -58,6 +58,13 @@
                   pièces</span
                 >
               </div>
+              <div class="flex items-center gap-2">
+                <IconLucideBox class="w-4 h-4" aria-hidden="true" />
+                <span
+                  >{{ type.productRequirements?.length || 0 }} produit(s)
+                  requis</span
+                >
+              </div>
             </div>
             <div class="card-actions justify-end mt-4">
               <button
@@ -99,6 +106,7 @@ import { useToast } from "~/composables/useToast";
 import IconLucidePlus from "~icons/lucide/plus";
 import IconLucidePackage from "~icons/lucide/package";
 import IconLucideLayoutGrid from "~icons/lucide/layout-grid";
+import IconLucideBox from "~icons/lucide/box";
 
 const { machineTypes, loading, loadMachineTypes, deleteMachineType } =
   useMachineTypesApi();