- Initial release of `pandasdate`.
- Introduces `DataFrame` subclass with date attribute.
- Custom `__str__` and `_repr_html_` for enhanced displays.
- File I/O methods (`to_csv`, `to_parquet`, `to_excel`, `to_pickle`) that preserve the date.
- `read` methods for all major file formats, reconstructing DataFrames with original date information.
This release lays a robust foundation for future enhancements, including potentially adding custom date operations and compatibility with additional file formats.