Merge main (82022306) into fix/flights-unpositioned-rows-complete

Resolve conflicts with main by keeping both sides:
- CHANGELOG.md: keep this PR's flights entry above main's newer entries.
- src/layers/flights/records.test.mjs: keep this PR's position-less
  retention test alongside main's civil emergency-status test.

src/sources/live/aircraft.js merged cleanly: openSkySnapshot keeps main's
emergencyByIcao normalizer and passes openSkyUnpositionedId to admitRecords.

Co-Authored-By: Claude Opus 5.5 <[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 +227,22 @@ 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,
+      // One source-switch omission may retain an ADS-B status, while an
+      // explicit clear or changed squawk always takes effect immediately.
+      emergency:
+        observation.emergency === undefined &&
+        observation.squawk === prevMeta?.squawk &&
+        prevMeta?.emergency?.source === 'ads-b' &&
+        (prevMeta?.missingEmergencyPolls ?? 0) < 1
+          ? prevMeta.emergency
+          : aircraftEmergency(observation),
+      missingEmergencyPolls:
+        observation.emergency === undefined
+          ? (prevMeta?.missingEmergencyPolls ?? 0) + 1
+          : 0,
       // 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