feat(booth): refusal snapshots, subscriber access medium, one-car-one-ticket entry

Three booth-integrity improvements that share the entry/exit flows and activity log.

Refusal snapshots: previously only an accepted open captured a camera image; now
every refusal/hold anomaly fires the directional camera too (a turned-away car is
exactly the evidence wanted) — entry refused-full/held, exit refused
closed/no-session/unpaid/grace-expired (booth + reader paths), refused subscription.
A refused entry has no ticket id, so a synthetic REFUSED- ref keys the anomaly + photo
together. Same fire-and-forget contract; failed captures still show as tiles.

Subscriber access medium: the subscription flow already signed `via`
(qr|card|plate) into entry/exit payloads; surface it as a typed LedgerPayload.via, a
cyan chip in the ticker, and an "Entry medium" modal row (sq+en). Display-only.

One car = one ticket: the entry button could be mashed to mint many tickets per car
(corrupting occupancy + enabling ticket-shopping at exit) — the old #inFlight guard
only blocked overlapping presses. Add a per-relay guard configured on the relay spec:
PRESENCE mode (presenceInput ties ticketing to a vehicle loop on a Dingtian input —
one ticket per car, re-armed when the loop clears) or COOLDOWN fallback
(entryCooldownSec) when there's no barrier feedback. A suppressed press is unsigned
device_events telemetry, not a signed anomaly. SetupWizard exposes both fields.
Fail-closed entry and barrier-is-not-a-door invariants untouched; guard state is
in-memory/rebuildable, starts armed after restart.

Wiki: new entry-double-press; updated entry-exit-points, booth-console, index.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

wiki/index.md

@@ -75,6 +75,7 @@ Counts: 4 sources · 19 entities · 44 concepts · 5 decision records.
 - [[challenge-response-auth]] — asymmetric nonce scheme for the ESP32 (auth + anti-replay).
 - [[entry-exit-readers]] — two populations, two integration paths; both can share a relay.
 - [[entry-exit-points]] — pool-of-spaces model (no lane); per-relay direction, reader→relay binding, camera snapshots.
+- [[entry-double-press]] — one car = one ticket: per-relay presence-loop gate (preferred) or cooldown fallback; suppressed press = telemetry.
 - [[uhppote-vs-esp32]] — comparison: detection vs. prevention.
 
 ## Concepts — business domain