Rename enum values to avoid conflict with windows.h DELETE macro

- Renamed `DELETE` to `OP_DELETE` in the `Operation` enum to avoid conflict with the DELETE macro defined in windows.h. - Updated all references to the enum values to use the new names (e.g., `OP_DELETE`, `OP_INSERT`, `OP_EQUAL`). - Ensured compatibility with existing code by making necessary adjustments where the enum was used. #21