feat(inventory): add InventorySubject enum and integrate into catalog item management

app/Domains/Purchase/Services/Checkout/StartCheckoutService.php

@@ -22,6 +22,7 @@ class StartCheckoutService
         private readonly UserPurchaseLimitService $purchaseLimits,
         private readonly CatalogSelectionResolver $selections,
         private readonly PurchaseItemSnapshotFactory $snapshots,
+        private readonly InsufficientStockMessageBuilder $stockMessages,
     ) {}
 
     /** @param array<string, mixed> $purchaseData */
@@ -128,17 +129,25 @@ class StartCheckoutService
 
             if ($availableQuantity !== null && $availableQuantity < $line['quantity']) {
                 throw ValidationException::withMessages([
-                    "{$line['field']}.cantidad" => __('api.purchase.direct_items_max_stock', [
-                        'max' => $availableQuantity,
-                    ]),
+                    "{$line['field']}.cantidad" => $this->stockMessages->build(
+                        $line['catalog_item'],
+                        $line['selection'],
+                        $availableQuantity,
+                    ),
                 ]);
             }
 
             try {
                 $this->inventory->reserve($line['selection'], $line['quantity']);
             } catch (\InvalidArgumentException) {
+                $availableQuantity = $this->inventory->availableQuantity($line['selection']) ?? 0;
+
                 throw ValidationException::withMessages([
-                    "{$line['field']}.cantidad" => __('api.purchase.insufficient_stock'),
+                    "{$line['field']}.cantidad" => $this->stockMessages->build(
+                        $line['catalog_item'],
+                        $line['selection'],
+                        $availableQuantity,
+                    ),
                 ]);
             }
         }