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/ui/cockpitInstruments.js

@@ -12,6 +12,7 @@ import {
   compassDivisions,
   formatAltitudeRulerTick,
   formatCompassDivision,
+  formatCockpitEmergency,
   formatSpeedRulerTick,
   normalizeHeading,
   relativeBearing,
@@ -133,7 +134,15 @@ export function updateHud(
         : info.stale
           ? 'STALE FEED'
           : 'LIVE TRACK';
-    this.aircraftMeta.textContent = `${info.layerId === 'military' ? 'MILITARY' : 'COMMERCIAL'} · ${feedState} · COURSE ALIGNED`;
+    const fleet = info.layerId === 'military' ? 'MILITARY' : 'COMMERCIAL';
+    const emergency = formatCockpitEmergency(info.emergency);
+    this.aircraftMeta.textContent = emergency
+      ? `${fleet} · ${emergency} · ${feedState}`
+      : `${fleet} · ${feedState} · COURSE ALIGNED`;
+    this.aircraftMeta.classList.toggle(
+      'emergency',
+      info.emergency?.severity === 'emergency',
+    );
   }
   this.updateRoute(info);
   if (