Add a changelog from the first release (2026.10.12.1) up to
2026.10.15.3, newest first, with Added/Changed/Removed/Fixed sections
and the commit behind each entry. List dark mode under 2026.10.15.3,
since it shipped without a version bump.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JZPd3GGWyxTgAkL6a4gAJz
