Fix module import error in dependencies

- Update models/__init__.py to properly export model classes
- Fix the AttributeError when referencing models.User in app/api/deps.py
- Ensure proper re-exports to satisfy linting requirements

app/models/__init__.py

@@ -1 +1,6 @@
-# models package initialization
+# models package initialization
+from app.models.user import User as User
+from app.models.category import Category as Category
+from app.models.supplier import Supplier as Supplier
+from app.models.product import Product as Product
+from app.models.inventory import Inventory as Inventory, InventoryTransaction as InventoryTransaction