• New: live_hires_mode: always — Frigate becomes only the trigger ("someone is on
  this camera") and FaceID decides from the full frame how many faces are present, instead
  of waiting for a snapshot to fail. Suggested in #8 for a case the fallback structurally
  cannot reach: if one of three arrivals is partly hidden, Frigate never tracks them as
  their own object, both other snapshots succeed, and that person stays invisible.
• Measured before shipping, and the numbers argue against making it the default. Seven
  days on a front-door camera: 59 events in 31 groups, and in 0 of 15 analysable groups
  did the full frame hold more faces than Frigate had reported events. It ran the other way
  — five events for a single visible face — because Frigate re-tracks a person as a new
  object when a track breaks. So fallback stays the default; always is there for setups
  where a busy entrance makes the case.
• A per-camera cooldown (live_hires_cooldown, default 2s) collapses the burst of events
  one group produces into a single frame fetch.
• In always, nothing found in the frame is bound to the Frigate event: the scan runs
  before the snapshot has established who the event is about, so the largest face may be
  someone else entirely. Those people are published and counted towards presence, while
  sub_label and the event score stay with the snapshot.