feat(layers): highlight aircraft broadcasting a transponder emergency

Flights and Military Flights tint aircraft red while the latest poll
carries squawk 7500/7600/7700 or an adsb.lol ADS-B emergency status
(general/unlawful/nordo/downed). Minimum-fuel and lifeguard priorities
are reported but not tinted. The Cockpit HUD aircraft-meta line names
the broadcast code in red. The status is not sticky: a cleared code
stops highlighting on the next refresh.

The analyst/voice query engine gains squawk, emergency and
emergencyKind fields. No new source or request: OpenSky state vectors
already carry the squawk and adsb.lol/readsb carries both fields.

Built by the Hex project (Crew Leo Agile dev team).

Co-Authored-By: Claude <[email protected]>

src/data/aircraftEmergency.test.mjs

@@ -0,0 +1,55 @@
+// src/data/aircraftEmergency.test.mjs
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  aircraftEmergency,
+  isEmergency,
+  normalizeSquawk,
+} from './aircraftEmergency.js';
+
+test('the three ICAO emergency squawks map to their kinds', () => {
+  assert.equal(aircraftEmergency({ squawk: '7500' }).kind, 'unlawful');
+  assert.equal(aircraftEmergency({ squawk: '7600' }).kind, 'nordo');
+  const general = aircraftEmergency({ squawk: ' 7700 ' });
+  assert.deepEqual(general, {
+    kind: 'general',
+    label: 'General emergency',
+    severity: 'emergency',
+    squawk: '7700',
+    source: 'squawk',
+  });
+});
+
+test('ordinary codes, blanks and non-octal values are not emergencies', () => {
+  for (const squawk of ['1200', '7000', '2000', '', null, undefined, '7800'])
+    assert.equal(aircraftEmergency({ squawk }), null, String(squawk));
+  assert.equal(aircraftEmergency(), null);
+  assert.equal(normalizeSquawk('7800'), null);
+  assert.equal(normalizeSquawk(7700), '7700');
+  assert.equal(normalizeSquawk('770'), null);
+});
+
+test('the ADS-B emergency field wins, and `none` defers to the squawk', () => {
+  const minfuel = aircraftEmergency({ squawk: '4521', emergency: 'MinFuel' });
+  assert.equal(minfuel.kind, 'minfuel');
+  assert.equal(minfuel.severity, 'priority');
+  assert.equal(minfuel.source, 'ads-b');
+  assert.equal(minfuel.squawk, '4521');
+  assert.equal(
+    aircraftEmergency({ squawk: '7700', emergency: 'none' }).source,
+    'squawk',
+  );
+  assert.equal(aircraftEmergency({ emergency: 'downed' }).kind, 'downed');
+  assert.equal(aircraftEmergency({ emergency: 'none' }), null);
+  assert.equal(aircraftEmergency({ emergency: 'reserved' }), null);
+});
+
+test('priority statuses are reported but are not emergencies', () => {
+  assert.equal(isEmergency(aircraftEmergency({ squawk: '7700' })), true);
+  assert.equal(
+    isEmergency(aircraftEmergency({ emergency: 'lifeguard' })),
+    false,
+  );
+  assert.equal(isEmergency(aircraftEmergency({ emergency: 'minfuel' })), false);
+  assert.equal(isEmergency(null), false);
+});