refactor: update module imports to use module locations

Update all module files to import from canonical module locations
instead of legacy re-export files:
- checkout, orders, customers routes: use module schemas
- catalog, marketplace schemas: use inventory module schemas
- marketplace, customers, inventory, analytics services: use module models

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

app/modules/marketplace/services/letzshop/order_service.py

@@ -23,7 +23,7 @@ from models.database.letzshop import (
     VendorLetzshopCredentials,
 )
 from models.database.marketplace_import_job import MarketplaceImportJob
-from models.database.order import Order, OrderItem
+from app.modules.orders.models import Order, OrderItem
 from models.database.product import Product
 from models.database.vendor import Vendor
 

app/modules/marketplace/services/marketplace_product_service.py

@@ -30,12 +30,12 @@ from app.exceptions import (
     ValidationException,
 )
 from app.utils.data_processing import GTINProcessor, PriceProcessor
-from models.database.inventory import Inventory
+from app.modules.inventory.models import Inventory
 from models.database.marketplace_product import MarketplaceProduct
 from models.database.marketplace_product_translation import (
     MarketplaceProductTranslation,
 )
-from models.schema.inventory import InventoryLocationResponse, InventorySummaryResponse
+from app.modules.inventory.schemas import InventoryLocationResponse, InventorySummaryResponse
 from models.schema.marketplace_product import (
     MarketplaceProductCreate,
     MarketplaceProductUpdate,