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/cockpitMath.js

@@ -83,6 +83,20 @@ export function cockpitAltitudeDisplayFt(altitudeM, onGround) {
   return Number.isFinite(altitudeM) ? altitudeM * 3.28084 : null;
 }
 
+/**
+ * HUD wording for a tracked aircraft's transponder emergency, or null.
+ * States the broadcast code, never a conclusion about the flight.
+ * @param {{label?: string, squawk?: string|null}|null|undefined} emergency
+ * @returns {string|null}
+ */
+export function formatCockpitEmergency(emergency) {
+  const label = String(emergency?.label || '')
+    .trim()
+    .toUpperCase();
+  if (!label) return null;
+  return emergency.squawk ? `SQUAWK ${emergency.squawk} · ${label}` : label;
+}
+
 /** Format the cockpit Context scope without overstating installation coverage. */
 export function formatCockpitContextScope(
   subjectLabel,