Instants (blocks, swaps, node starts) render in the viewer's zone and say
which: tables carry the zone, charts name it once, titles give UTC. Daily
buckets the API cut at UTC midnight render in UTC and are headed "(UTC)" —
FlowChart formatted them as local dates, putting every bar a day early
anywhere west of Greenwich.
All date formatting goes through lib/format.ts (when, utc, clock, utcDay,
utcMonth, zone), one locale and a 24-hour clock. `pnpm test` runs Node's
built-in runner under America/New_York, where the old formatter turns
5 Oct into 4 Oct, and is part of the shared CI gate.
Closes#38
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015pkwBsR54NRmZyU4QVhvfj
