plan/STATUS.md: what the last session changed, what to pick up next, and the
handful of things that were learned the hard way and would otherwise have to
be rediscovered. Linked from the overview, which now also lists plans 13 and
14 alongside the earlier phases.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015CYEJKobJ2Re4Dv7qUoSA7
