Merge rebased aircraft emergency contribution for HAL-522 validation

# Conflicts:
#	DATA_SOURCES.md

src/sources/live/aircraft.js

@@ -30,6 +30,9 @@ export function normalizeOpenSkyAircraft(row) {
     typeCode: null,
     registration: null,
     operator: null,
+    squawk: cleanText(row[14]) || null,
+    // State vectors carry no ADS-B emergency field; the squawk stands alone.
+    emergency: null,
   };
 }
 
@@ -68,6 +71,8 @@ export function normalizeReadsbAircraft(row, snapshotTimeMs) {
     typeCode: cleanText(row.t),
     registration: cleanText(row.r),
     operator: cleanText(row.ownOp),
+    squawk: cleanText(row.squawk) || null,
+    emergency: cleanText(row.emergency).toLowerCase() || null,
   };
 }
 

src/sources/live/contract.test.mjs

@@ -313,3 +313,23 @@ test('identity lookup validates its response and honors body-parse cancellation'
     name: 'AbortError',
   });
 });
+
+test('transponder squawk and ADS-B emergency status are carried, blanks stay null', () => {
+  const squawking = [...aircraft, '7700'];
+  const civil = openSkySnapshot({ states: [squawking] }, { now }).records[0];
+  assert.equal(civil.squawk, '7700');
+  assert.equal(civil.emergency, null);
+  assert.equal(openSkySnapshot({ states: [aircraft] }).records[0].squawk, null);
+  const mil = normalizeReadsbAircraft(
+    { hex: 'abc123', lat: 30, lon: -97, squawk: '7600', emergency: 'NORDO' },
+    now,
+  );
+  assert.equal(mil.squawk, '7600');
+  assert.equal(mil.emergency, 'nordo');
+  const quiet = normalizeReadsbAircraft(
+    { hex: 'abc123', lat: 30, lon: -97 },
+    now,
+  );
+  assert.equal(quiet.squawk, null);
+  assert.equal(quiet.emergency, null);
+});