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/lane-presence.test.ts

@@ -0,0 +1,144 @@
+import { beforeEach, describe, expect, it } from "vitest";
+import { eq, devices, type Db } from "@parking/db";
+import { createTestDb } from "@parking/db/testing";
+import { LanePresence } from "./lane-presence.js";
+import { deviceEvents, type DeviceInputEvent, type LanePresenceEvent } from "./device-events.js";
+import { silentLogger } from "./test-helpers.js";
+
+// LanePresence: a vehicle-presence INPUT edge (loop/radar) on an entry/exit barrier marks
+// that lane "present" — the same signal that blinks the physical button lamp (relay 3). It
+// resolves the edge via relayForPresence (the SAME path relay 3 + the entry gate use), and
+// emits a lane-presence change only when a lane's present/clear state actually flips.
+
+let db: Db;
+const CTL = "ctl-1";
+const ENTRY_RADAR = 2;
+const EXIT_RADAR = 5;
+
+beforeEach(() => {
+  ({ db } = createTestDb());
+  // Entry relay 1 with a radar on I2; exit relay 2 with a radar on I5.
+  db.insert(devices).values({
+    id: CTL,
+    category: "access",
+    driverId: "dingtian",
+    config: {
+      host: "10.0.0.5",
+      relays: [
+        { relay: 1, direction: "entry" },
+        { relay: 2, direction: "exit" },
+      ],
+      inputs: [
+        { input: ENTRY_RADAR, role: "presence", relay: 1, kind: "radar" },
+        { input: EXIT_RADAR, role: "presence", relay: 2, kind: "radar" },
+      ],
+    },
+    enabled: true,
+  }).run();
+});
+
+function edge(input: number, on: boolean): void {
+  const e: DeviceInputEvent = {
+    driverId: "dingtian",
+    deviceId: CTL,
+    input,
+    edge: on ? "on" : "off",
+    at: new Date().toISOString(),
+    source: "poll",
+  };
+  deviceEvents.emitInput(e);
+}
+
+/** Collect lane-presence emissions while running `fn`. */
+function capture(fn: () => void): LanePresenceEvent[] {
+  const seen: LanePresenceEvent[] = [];
+  const off = deviceEvents.onLanePresence((p) => seen.push(p));
+  try {
+    fn();
+  } finally {
+    off();
+  }
+  return seen;
+}
+
+describe("LanePresence", () => {
+  it("starts clear and snapshots clear", () => {
+    const lp = new LanePresence(db, silentLogger());
+    lp.start();
+    expect(lp.snapshot()).toEqual({ entry: false, exit: false });
+    lp.stop();
+  });
+
+  it("an ENTRY radar edge marks the entry lane present, then clears", () => {
+    const lp = new LanePresence(db, silentLogger());
+    lp.start();
+    const events = capture(() => {
+      edge(ENTRY_RADAR, true);
+      edge(ENTRY_RADAR, false);
+    });
+    expect(events).toEqual([
+      { entry: true, exit: false },
+      { entry: false, exit: false },
+    ]);
+    lp.stop();
+  });
+
+  it("an EXIT radar edge marks the exit lane independently", () => {
+    const lp = new LanePresence(db, silentLogger());
+    lp.start();
+    const events = capture(() => {
+      edge(EXIT_RADAR, true);
+    });
+    expect(events).toEqual([{ entry: false, exit: true }]);
+    expect(lp.snapshot()).toEqual({ entry: false, exit: true });
+    lp.stop();
+  });
+
+  it("de-dupes: a second 'on' from another presence input on the same lane emits once", () => {
+    // Two radars both serving the entry lane.
+    db.update(devices)
+      .set({
+        config: {
+          host: "10.0.0.5",
+          relays: [{ relay: 1, direction: "entry" }],
+          inputs: [
+            { input: 2, role: "presence", relay: 1, kind: "radar" },
+            { input: 3, role: "presence", relay: 1, kind: "radar" },
+          ],
+        },
+      })
+      .where(eq(devices.id, CTL))
+      .run();
+    const lp = new LanePresence(db, silentLogger());
+    lp.start();
+    const events = capture(() => {
+      edge(2, true); // entry → present (emit)
+      edge(3, true); // still present (no emit — same lane)
+      edge(2, false); // still present via I3 (no emit)
+      edge(3, false); // now clear (emit)
+    });
+    expect(events).toEqual([
+      { entry: true, exit: false },
+      { entry: false, exit: false },
+    ]);
+    lp.stop();
+  });
+
+  it("ignores a non-presence input (e.g. a button terminal)", () => {
+    db.update(devices)
+      .set({
+        config: {
+          host: "10.0.0.5",
+          relays: [{ relay: 1, direction: "entry" }],
+          inputs: [{ input: 1, role: "button", relay: 1 }],
+        },
+      })
+      .where(eq(devices.id, CTL))
+      .run();
+    const lp = new LanePresence(db, silentLogger());
+    lp.start();
+    const events = capture(() => edge(1, true));
+    expect(events).toEqual([]);
+    lp.stop();
+  });
+});