feat(booth): blink the Entry/Exit lights on radar presence (mirror relay 3)

The on-screen Hyrje/Dalje barrier lights were 2-state (green=free / red=busy)
off the camera lane-status only — they couldn't show the radar-only "detected,
not yet confirmed" state that makes the physical button lamp (relay 3) blink.
Now they mirror the lamp's 3-state rule per lane:
  radar present + camera not busy → BLINK green↔red (~1 Hz)
  camera busy                     → SOLID red
  otherwise                       → SOLID green

End-to-end:
- LanePresence (lane-presence.ts): subscribes to deviceEvents.onInput, resolves
  each presence edge to its lane via the new direction-agnostic presenceLaneOf()
  (device-resolve.ts) — entry AND exit, unlike the entry-gated relayForPresence
  the one-car-one-ticket gate uses — and emits a lane-presence {entry,exit} bus
  event on change. Wired in server.ts (start + onClose).
- WS forwards it (hello snapshot + push) into live-store.radar.
- BarrierLight (BoothScreen.tsx) is now 3-state; blinks via the .lane-blink
  keyframe (index.css), which holds solid-red under prefers-reduced-motion.

Same input + same rule as the lamp, so the screen and the post never disagree.

A new test (lane-presence.test.ts) caught a real bug: the first cut reused
relayForPresence, so the EXIT lane never resolved (it's entry-gated) and never
blinked — presenceLaneOf fixes it. Covers entry/exit independence, de-dupe
across several radars on one lane, and ignoring non-presence inputs.

Full workspace build/lint/test green (185 server tests). Updated the
button-light-indicator wiki page ("On-screen twin").

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

apps/server/src/device-resolve.ts

@@ -224,6 +224,26 @@ export function alertRelaysOf(row: DeviceRow): RelaySpec[] {
   return relaysOf(row).filter((r) => r.direction === "radarAlert" && typeof r.relay === "number");
 }
 
+/**
+ * Which LANE a presence input belongs to — for the booth's barrier-light blink (advisory).
+ * Unlike `relayForPresence` (entry-gated, for the one-car-one-ticket gate), this resolves a
+ * presence input on ANY barrier: entry/both → "entry", exit → "exit". Returns null if the
+ * terminal isn't a presence input on a barrier relay. See lane-presence.ts.
+ */
+export function presenceLaneOf(db: Db, controllerId: string, terminal: number): FlowDirection | null {
+  const row = db
+    .select()
+    .from(devices)
+    .where(and(eq(devices.id, controllerId), eq(devices.category, "access")))
+    .get();
+  if (!row || !row.enabled) return null;
+  const presence = inputsOf(row).find((i) => i.role === "presence" && i.input === terminal);
+  if (!presence || typeof presence.relay !== "number") return null;
+  const relay = relaysOf(row).find((r) => r.relay === presence.relay);
+  if (!relay) return null;
+  return relay.direction === "exit" ? "exit" : relay.direction === "radarAlert" ? null : "entry";
+}
+
 /**
  * Resolve a reader/camera to the relay it opens. Preferred: its config binding
  * (controllerId + relay) → exactly that barrier, direction inherited from the relay