feat: add provisional Table component

[rmartins90]

Related: https://github.com/Doist/frontend-issues/issues/1369

Short description

Adds a provisional Reactist Table prototype based on Todoist's current flat data table for review during the Reactist session.

• Preserves native table markup, typed columns and data, stable row IDs, controlled manual sorting, empty states, custom rows and cells, and selected-row styling.
• Exposes TableRow and TableCell building blocks without making the CSS module public.
• Adds presentation-ready Data Display stories for default, sorting, selection, empty, placeholder-row, and narrow viewport states.
• Pins and externalizes @tanstack/react-table 8.21.3.

The API is intentionally provisional. This does not add hierarchy, drag and drop, multi-select, persistence, responsive redesign, or Todoist integration.

To review in Storybook:

1. Run npm run storybook.
2. Open Data display / Table / Default and try sorting with pointer and keyboard.
3. Open Selected and clickable rows, then activate rows with pointer, Enter, and Space.
4. Review the empty, custom placeholder, and narrow viewport stories.

PR Checklist

• Added tests for bugs / new features
• Updated docs (storybooks, readme)
• Reviewed and approved Chromatic visual regression tests in CI