• The live hi-res frame now recognises everyone in it, not just the largest face.
  A full frame frequently holds more than one person — measured, 5 of 12 door events. Until
  now best_face() kept the biggest and discarded the rest, so whoever stood closest won.
• Frigate creates one event per person, so a group normally still works out. But when one
  of those events has no usable snapshot, that person was dropped — even though their face
  is plainly visible in the very frame we just fetched for someone else. Exactly the case
  from #8: several people arriving together, one recognised late or not at all.
• Every recognised person is published and counted towards the camera's presence sensor,
  which has always held a set of people. Only the largest face binds to the event
  (sub_label takes a single name, and best_score belongs to the person the event is
  about). Uncertain secondary faces are not queued for review — the queue should show the
  subject of the event, not passers-by in the background.
• Fixed along the way: the per-event "already announced" marker held a single name, so two
  known people in one frame would overwrite each other and be re-announced in turn — the
  duplicate notifications that marker exists to prevent. It is a set now.