Per request. /attendance is now a client view: a 'Here now' section
with host badges + inline self check-in / check-in-as-host / check-out
with a note; and a history with name search, a day picker, grouped-by-
day headers, per-visit duration, status, notes, and a live
visits/members summary for the current filter. New pure tested helpers
dayKey (tz-stable UTC bucket) + visitDurationMinutes (+5 tests, suite
459).