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/military/records.test.mjs

@@ -98,3 +98,19 @@ test('military records keep bounded partial retention and release metadata only
     'remove',
   );
 });
+
+test('military emergency status follows the latest poll instead of sticking', () => {
+  const records = store();
+  const first = records.receive(
+    observation({ squawk: '1234', emergency: 'minfuel' }),
+    context(),
+  );
+  assert.equal(first.meta.squawk, '1234');
+  assert.equal(first.meta.emergency.kind, 'minfuel');
+  assert.equal(first.meta.emergency.severity, 'priority');
+  const next = records.receive(
+    observation({ squawk: '1234', emergency: 'none' }),
+    context(),
+  );
+  assert.equal(next.meta.emergency, null);
+});