Conflict: layout/flow.rs imports take both MAX_INSTANCES (this PR) and
MAX_MEASURES (main). Main's new check-box width arm in measure() now
passes the &Ctx this PR's per-instance measure takes.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Pq7HyCHD1R3rywQBPCHXZA