fix: correct service methods and add inventory schema model

Services:
- admin_service: Add source_url to import job response, fix vendor_name
  to use vendor.name relationship instead of vendor_name field
- marketplace_product_service: Include reserved_quantity and
  available_quantity in InventoryLocationResponse
- vendor_service: Fix _get_product_by_id_or_raise to use database ID
  (int) instead of marketplace_product_id (str)

Schema:
- Add InventorySummaryResponse model for marketplace product service

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

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

app/services/vendor_service.py

@@ -539,16 +539,16 @@ class VendorService:
         )
 
     def _get_product_by_id_or_raise(
-        self, db: Session, marketplace_product_id: str
+        self, db: Session, marketplace_product_id: int
     ) -> MarketplaceProduct:
-        """Get product by ID or raise exception."""
+        """Get marketplace product by database ID or raise exception."""
         product = (
             db.query(MarketplaceProduct)
-            .filter(MarketplaceProduct.marketplace_product_id == marketplace_product_id)
+            .filter(MarketplaceProduct.id == marketplace_product_id)
             .first()
         )
         if not product:
-            raise MarketplaceProductNotFoundException(marketplace_product_id)
+            raise MarketplaceProductNotFoundException(str(marketplace_product_id))
         return product
 
     def _product_in_catalog(