V05 PRESENTER DISPLAY BOUNDARY CHECK
IN: one fixed synthetic schedule, one shared schedule_id, presenter redaction, facilitator pause/next/finish/fallback labels
OUT: live cross-window sync, network, account, upload, input, localStorage, timer runtime mutation, analytics
CHECKPOINTS: 600 -> 510 -> 180 -> 0 seconds
ROLLBACK: remove only the V05 guide routes, V05 fixture files, sitemap entries and focused checks