[FEAT] 優化庫存分析邏輯，增加銷售 Reference Type 追蹤並修正 InventoryService 閉包變數問題

tests/Feature/Integration/PosApiTest.php

@@ -175,6 +175,9 @@ class PosApiTest extends TestCase
             'Accept' => 'application/json',
         ])->postJson('/api/v1/integration/orders', $payload);
 
+        $response->assertStatus(201)
+                 ->assertJsonPath('message', 'Order synced and stock deducted successfully');
+
         $response->assertStatus(201)
                  ->assertJsonPath('message', 'Order synced and stock deducted successfully');
 
@@ -196,6 +199,14 @@ class PosApiTest extends TestCase
             'warehouse_id' => $warehouseId,
             'quantity' => 95,
         ]);
+
+        $order = \App\Modules\Integration\Models\SalesOrder::where('external_order_id', 'ORD-001')->first();
+        $this->assertDatabaseHas('inventory_transactions', [
+            'reference_type' => \App\Modules\Integration\Models\SalesOrder::class,
+            'reference_id' => $order->id,
+            'quantity' => -5,
+            'type' => '出庫',
+        ]);
         
         tenancy()->end();
     }