fix: correct inventory service and test for product model changes

- Fix inventory_service.py: use product.vendor_sku instead of non-existent product.product_id
- Fix test: create MarketplaceProductTranslation for title (now in translations table)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/unit/services/test_inventory_service.py

@@ -368,15 +368,24 @@ class TestInventoryService:
         # Create a new product without inventory
         from models.database.product import Product
         from models.database.marketplace_product import MarketplaceProduct
+        from models.database.marketplace_product_translation import MarketplaceProductTranslation
 
         unique_id = str(uuid.uuid4())[:8]
         mp = MarketplaceProduct(
             marketplace_product_id=f"MP_EMPTY_{unique_id}",
-            title="Product Without Inventory",
             price="29.99",
             marketplace="Letzshop",
         )
         db.add(mp)
+        db.flush()
+
+        # Create translation for the product (title is now in translations table)
+        translation = MarketplaceProductTranslation(
+            marketplace_product_id=mp.id,
+            language="en",
+            title="Product Without Inventory",
+        )
+        db.add(translation)
         db.commit()
 
         product = Product(