feat(backend): add BizSampleFreight models

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models/__init__.py

@@ -49,6 +49,8 @@ from app.models.models import (
     BizProductionTaskStepDataCollection,
     BizProductionTaskOutput,
     BizStorageSlotOccupancy,
+    BizSampleFreight,
+    BizSampleFreightItem,
 )
 from app.models.production_material import (  # noqa: F401
     BizProductionMaterial,
@@ -123,6 +125,8 @@ __all__ = [
     "BizProductionTaskStepDataCollection",
     "BizProductionTaskOutput",
     "BizStorageSlotOccupancy",
+    "BizSampleFreight",
+    "BizSampleFreightItem",
     "BizProductionMaterial",
     "BizProductionMaterialStockBatch",
     "BizProductionMaterialUsage",