Extend markdown_to_notion_blocks with GFM table support and rewrite
parse_rich_text to emit Notion annotations for bold/italic/code/link/strike
instead of dropping them as literal text. Move checkbox match ahead of the
bullet match so "- [ ]" lines become to_do blocks, not bullets.
Add test_parser.py with 13 regression tests covering rich-text spans,
block types, and table cell formatting.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
