Merge upstream/main: air-quality layer (AQHI) meets i18n

Upstream's #568 adds the Air quality layer to the Weather group (ECCC
AQHI, Canada only) with a band legend, worst-first list and voice
support.

- package-boundaries: both sides' entries unioned.
- layerPanel/weatherPanel tests: both sides' new tests kept; the
  weatherPanel fixture follows upstream (legendCategorical: true, the
  'list' block id) while our localized-history (K-6) test stays.
- air-quality strings marked: band labels and the provider label as
  msg() data, the readings-list aria-label through t(); es/ru entries
  added (+6 keys each).
- The synthetic air-quality allocation-benchmark titles follow the
  file's own convention (// i18n-ignore) like TRK/VESSEL/CAMERA.

Also verified the auto-merged weatherPanel.js against upstream: ORDER
gains 'air-quality', OBSERVED stays slice(2, 5), and the data-driven
legendCategorical path is upstream's.

npm run i18n: complete (2559), no unmarked strings. npm test: only the
pre-existing environmental OPENAI_API_KEY leak fails. Build passes.

src/sources/reference.js

@@ -1,4 +1,5 @@
 import { createUsgsEarthquakeSource } from '../layers/earthquakes/source.js';
+import { createEcccAirQualitySource } from '../layers/airQuality/source.js';
 import { createWfigsPerimeterSource } from '../layers/perimeters/source.js';
 import { createBundledCableSource } from '../layers/submarineCables/bundledSource.js';
 import { createAdsbGnssSource } from '../layers/gnss/source.js';
@@ -7,6 +8,7 @@ import { createAdsbGnssSource } from '../layers/gnss/source.js';
 export function createReferenceSources() {
   return {
     earthquakes: createUsgsEarthquakeSource(),
+    'air-quality': createEcccAirQualitySource(),
     'fire-perimeters': createWfigsPerimeterSource(),
     cables: createBundledCableSource(),
     'gnss-integrity': createAdsbGnssSource(),

src/sources/reference.test.mjs

@@ -14,15 +14,18 @@ test('reference factories retain compatibility without starting acquisition or s
   const second = createReferenceSources();
   assert.deepEqual(Object.keys(first), [
     'earthquakes',
+    'air-quality',
     'fire-perimeters',
     'cables',
     'gnss-integrity',
   ]);
   assert.notEqual(first.earthquakes, second.earthquakes);
+  assert.notEqual(first['air-quality'], second['air-quality']);
   assert.notEqual(first['fire-perimeters'], second['fire-perimeters']);
   assert.notEqual(first.cables, second.cables);
   assert.notEqual(first['gnss-integrity'], second['gnss-integrity']);
   assert.equal(typeof first.earthquakes.getSnapshot, 'function');
+  assert.equal(typeof first['air-quality'].getSnapshot, 'function');
   assert.equal(typeof first['fire-perimeters'].getSnapshot, 'function');
   assert.equal(typeof first.cables.fetch, 'function');
   assert.equal(typeof first['gnss-integrity'].getSnapshot, 'function');