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/layers/flights/records.js

@@ -4,6 +4,7 @@ import {
   pickRenderAltitudeM,
 } from '../../data/renderAltitude.js';
 import { classifyAircraft } from '../../data/aircraftClass.js';
+import { aircraftEmergency } from '../../data/aircraftEmergency.js';
 import {
   approxDistanceKm,
   GROUND_FLOOR_CLAMP_RADIUS_KM,
@@ -226,6 +227,10 @@ export class FlightRecords {
       // like callsign so a transient blank row doesn't blank the field.
       originCountry:
         stickyText(origin_country, prevMeta?.originCountry) || null,
+      // Per poll, NOT sticky: an emergency code clears when the crew resets
+      // it, so a blank squawk must not hold a stale 7700 on screen.
+      squawk: observation.squawk ?? null,
+      emergency: aircraftEmergency(observation),
       // OpenSky distinguishes the last position epoch from the last
       // transponder message. The fleet coast horizon uses this actual
       // contact time so a temporarily old position does not hard-freeze