Tables render poorly in Telegram (pipes stripped, whitespace collapses).
This adds a 'tableMode' option to markdownToIR that converts tables to
nested bullet points, which render cleanly on mobile.
- Add tableMode: 'flat' | 'bullets' to MarkdownParseOptions
- Track table state during token rendering
- Render tables as bullet points with first column as row labels
- Apply bold styling to row labels for visual hierarchy
- Enable tableMode: 'bullets' for Telegram formatter
Closes #TBD
