Refactor DataTab to use scrollable DataTable for data preview

[jacopoprandelli]

Summary
Replace the Rich Table preview with Textual’s DataTable, wrapping it in HorizontalScroll so wide Parquet schemas stay accessible while preserving formatting. This is just one possible implementation.

Changes

• Swap _create_data_table to build a Textual DataTable (cursor support, zebra stripes, border styling, NULL highlighting).
• Size columns via header-based min_width and wrap the widget in HorizontalScroll inside compose so wide schemas remain accessible.
• Yield Static error/empty states through the Textual compose API to match the new widget structure.

Closes #23

[raulcd]

To be honest I plan to do quite a big overhaul of the initially hacked TUI to make it more composable. I'll take a look at your PR once I have some time and will probably merge it but then I'll refactor. For example there's quite a lot of logic on this module that doesn't belong here and should live in the reader.

[jacopoprandelli]

Yeah it makes sense. Thanks for the great tool!

[raulcd]

Thanks again for the PR. As suggested I plan to refactor the tui soon but I'll base it on your work here. Thanks for the changes!
Just a small nit about some of the attributes which doesn't seem strictly necessary when creating a DataTable.