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/web/src/BoothScreen.tsx

@@ -112,40 +112,45 @@ function TicketInput({ onSubmit }: { onSubmit: (identity: string) => void }) {
   );
 }
 
-/** One barrier light — green = free, red = busy (a vehicle is at the lane vicinity,
- *  from camera detection). Advisory only; it gates nothing. */
-function BarrierLight({ label, busy }: { label: string; busy: boolean }) {
+/** One barrier light — a 3-state indicator mirroring the physical button lamp (relay 3):
+ *  - radar present + camera NOT busy → BLINK green↔red (~1 Hz): "detected, not yet confirmed"
+ *  - camera busy → SOLID red: a vehicle is confirmed at the lane vicinity
+ *  - otherwise → SOLID green: free
+ *  Advisory only; it gates nothing. The blink uses the `.lane-blink` keyframe (index.css),
+ *  whose children inherit the alternating colour via `currentColor`. */
+function BarrierLight({ label, busy, radar }: { label: string; busy: boolean; radar: boolean }) {
+  // Blink only when the radar sees something the camera hasn't confirmed.
+  const blinking = radar && !busy;
+  const solid = busy ? "border-term-red bg-term-red/10 text-term-red" : "border-term-green bg-term-green/10 text-term-green";
   return (
     <div
-      className={`flex items-center gap-2 rounded-term border px-3 py-2 ${
-        busy ? "border-term-red bg-term-red/10" : "border-term-green bg-term-green/10"
-      }`}
+      className={`flex items-center gap-2 rounded-term border px-3 py-2 ${blinking ? "lane-blink" : solid}`}
       title={label}
     >
-      {/* Barrier glyph: a post + an arm. Colour carries the state. */}
-      <svg viewBox="0 0 24 24" className={`h-5 w-5 ${busy ? "text-term-red" : "text-term-green"}`} fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round">
+      {/* Barrier glyph: a post + an arm. `currentColor` follows the (possibly blinking) state. */}
+      <svg viewBox="0 0 24 24" className="h-5 w-5" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round">
         <line x1="5" y1="21" x2="5" y2="9" />
         <line x1="5" y1="10" x2="21" y2="6" />
         <circle cx="5" cy="7" r="1.6" fill="currentColor" stroke="none" />
       </svg>
       <div className="leading-tight">
         <div className="text-[10px] uppercase tracking-wider text-term-muted">{label}</div>
-        <div className={`text-xs font-bold ${busy ? "text-term-red" : "text-term-green"}`}>
-          {busy ? "●" : "○"}
-        </div>
+        <div className="text-xs font-bold">{busy ? "●" : blinking ? "◐" : "○"}</div>
       </div>
     </div>
   );
 }
 
-/** The two lane barrier lights (entry / exit) fed by the live lane-status. */
+/** The two lane barrier lights (entry / exit) fed by the live lane-status (camera busy/free)
+ *  and lane-presence (radar). */
 function LaneIndicators() {
   const { t } = useTranslation();
   const lanes = useLiveStore((s) => s.lanes);
+  const radar = useLiveStore((s) => s.radar);
   return (
     <div className="flex items-center gap-2">
-      <BarrierLight label={t("booth.laneEntry")} busy={lanes?.entry ?? false} />
-      <BarrierLight label={t("booth.laneExit")} busy={lanes?.exit ?? false} />
+      <BarrierLight label={t("booth.laneEntry")} busy={lanes?.entry ?? false} radar={radar?.entry ?? false} />
+      <BarrierLight label={t("booth.laneExit")} busy={lanes?.exit ?? false} radar={radar?.exit ?? false} />
     </div>
   );
 }