refactor: restructure item interfaces and update related components

- Renamed LineItem interface to Item and adjusted properties accordingly.
- Updated CreateItemData and UpdateItemData interfaces to reflect new structure.
- Modified components to use the new Item interface, removing nested lines.
- Adjusted data binding in item configuration, main data, and other related components.
- Simplified item creation and editing logic by removing unnecessary nesting.
- Ensured all references to line items are updated to reflect the new structure.

backend/api/v1/modules/a76/items/line_quantities/models.py

@@ -7,7 +7,7 @@ from core.database import Base
 from api.v1.modules.a76.general_catalogs.packages.models import Package
 
 if TYPE_CHECKING:
-    from ..line_items.models import LineItem
+    from ..models import LineItem
     
 class LineQuantity(Base):
     """