Multi-line <details>...</details> with optional <summary> emits a Notion
toggle block. Body recurses through _parse_lines so any block type
(lists, code, nested toggles) is supported inside. Depth tracking lets
<details> nest inside <details>. Unclosed <details> at EOF degrades to
plain paragraphs with a stderr warning instead of crashing.
+4 tests, 26 passing total.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Andrew Yim
aac1082bb7