feat(entry): admin bypass of the presence gate for faulty radar/camera

The entry button (physical press AND the operator-issued mint) requires
radar/loop presence + camera detection to confirm a real vehicle. When one
of those devices is faulty, the gate blocks legitimate transient entry. Let
the ADMIN drop a specific signal as a requirement until support fixes the
hardware — the admin is not the adversary, but weakening an anti-fraud gate
stays attributed and auditable:

- Granular: bypass radar and camera independently (Setup → controller
  section). A dead camera drops only the camera check; a dead radar only
  radar. Both off = normal gate; both on = press-to-print.
- Signed: a DEDICATED endpoint (PUT /api/site-config/presence-bypass,
  site:update) appends a signed config_change {setting, value, prev,
  operator} per actually-changed signal — new ledger type. No-op toggles
  sign nothing; disabling signs too. Kept out of the generic site PUT.
- Flagged: every vehicle_entry issued (and every refusal anomaly) while
  bypassed carries presenceBypassed:[...] in its signed payload.
- Persists until turned off; amber warning in Setup while active. The
  booth entry light treats a bypassed signal as satisfied (server
  re-checks authoritatively). Physical-button path falls through to the
  cooldown backstop when radar is bypassed.
- Migration 0020: two boolean site_config columns (default off).

Fixes a latent bug surfaced by the tests: firstRelayByDirection returned no
presenceInput, so issueForOperator's radar gate always read "presence loop
unavailable" — operator-issue never actually gated on radar. The resolver
now attaches the presence input serving the relay (mirrors relayForButton).

10 new tests: 5 gate combinations (each bypass drops only its signal +
records it), 5 route tests (RBAC, signed transitions, no-op, validation).

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

packages/shared/src/index.ts

@@ -265,6 +265,13 @@ export type LedgerEventType =
   // touch the drawer balance. Append-only, signed, so the decision is itself auditable.
   // See wiki/concepts/shift.md.
   | "cash_review"
+  // Signed record of an admin changing a FRAUD-RELEVANT setting, so the change is
+  // itself in the tamper-evident chain (who/when/what). Payload: { setting, value,
+  // operator, prev? }. First use: the entry presence-gate bypass (a faulty radar/
+  // camera lets the admin drop that signal as a requirement until support fixes it —
+  // the admin is NOT the adversary, but weakening an anti-fraud gate must still be
+  // attributed + auditable). See wiki/concepts/entry-presence-bypass.md.
+  | "config_change"
   | "anomaly";
 
 /** How money was tendered (for payment events + the shift Z-report). */