Major rewrite of hybrid mode around a per-block source/render toggle (the
cursor's paragraph swaps to literal markdown source, every other block stays
rendered) plus Obsidian-style link support, bold-italic and heading marker
de-duplication, reliable list Enter / Backspace, and several smaller editing
bug fixes. See CHANGELOG.md for the full list.

CDN reference in README bumped to v0.2.16.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>