- Add reopenRound() to round engine (CLOSED → ACTIVE) with auto-pause of subsequent active rounds
- Add reopen endpoint to roundEngine router and UI button on round detail page
- Replace free-text MIME type input with toggle-only badge buttons in file requirements editor
- Enable refetchOnWindowFocus and shorter polling intervals for readiness checklist queries
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>