fix(phase1): add photo fields to schemas and set datetime default

backend/tests/test_schema.py

@@ -34,7 +34,9 @@ class TestItemPhotoFields:
         retrieved = test_db.query(Item).filter_by(id=item.id).first()
         assert retrieved.photo_path is None
         assert retrieved.photo_thumbnail_path is None
-        assert retrieved.photo_upload_date is None
+        # photo_upload_date now has a default of datetime.now, so it should be populated
+        assert retrieved.photo_upload_date is not None
+        assert isinstance(retrieved.photo_upload_date, datetime)
 
     def test_photo_fields_can_store_values(self, test_db):
         """Test that photo fields can store string and datetime values."""
@@ -78,4 +80,6 @@ class TestItemPhotoFields:
         retrieved = test_db.query(Item).filter_by(id=item.id).first()
         assert retrieved.photo_path == "/images/items/photo-003.jpg"
         assert retrieved.photo_thumbnail_path is None
-        assert retrieved.photo_upload_date is None
+        # photo_upload_date gets default timestamp even when explicitly set to None
+        assert retrieved.photo_upload_date is not None
+        assert isinstance(retrieved.photo_upload_date, datetime)