feat(catalog): implement maximum addable quantity logic and user quota sharing across variants

app/Domains/Catalog/Resources/CatalogItemDetailResource.php

@@ -6,6 +6,7 @@ use App\Domains\Catalog\Enums\InventoryPolicy;
 use App\Domains\Catalog\Models\CatalogItem;
 use App\Domains\Catalog\Models\ItemAttribute;
 use App\Domains\Catalog\Models\Variant;
+use App\Domains\Catalog\Services\CatalogItemAllowanceService;
 use App\Domains\Shared\Enums\FieldType;
 use App\Domains\Ticket\Resources\ValidityTimeResource;
 use Illuminate\Http\Request;
@@ -41,6 +42,10 @@ class CatalogItemDetailResource extends JsonResource
                 $selectedVariant === null,
                 fn () => $this->availableStock(),
             ),
+            'maximum_addable_quantity' => $this->when(
+                $selectedVariant === null,
+                fn () => $this->maximumAddable($this->availableStock()),
+            ),
             'images' => $this->when(
                 $selectedVariant === null,
                 fn () => $this->imageUrls($this->attachments),
@@ -168,6 +173,7 @@ class CatalogItemDetailResource extends JsonResource
             'descripcion' => $variant->getDescription(),
             'precio' => number_format($variant->getPrice(), 2, '.', ''),
             'stock_tecnico' => $this->variantStock($variant),
+            'maximum_addable_quantity' => $this->maximumAddable($this->variantStock($variant)),
             'values' => $values,
         ];
     }
@@ -186,4 +192,12 @@ class CatalogItemDetailResource extends JsonResource
             ? null
             : $variant->inventory->availableStock();
     }
+
+    private function maximumAddable(?int $stock): ?int
+    {
+        return app(CatalogItemAllowanceService::class)->maximumAddableQuantity(
+            $stock,
+            $this->getAttribute('remaining_user_quota'),
+        );
+    }
 }