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.

scripts/package-boundaries.json

@@ -2427,7 +2427,11 @@
       "src/layers/installations/classLabel.js",
       "src/data/cameraFraming.js",
       "src/data/geoImportPins.js",
-      "src/data/geoImportImages.js"
+      "src/data/geoImportImages.js",
+      "src/app/layers/airQuality.js",
+      "src/layers/airQuality/index.js",
+      "src/layers/airQuality/model.js",
+      "src/layers/airQuality/source.js"
     ],
     "external": [
       "hls.js",
@@ -2986,7 +2990,11 @@
       "src/ui/unitLabels.js",
       "src/layers/recentImagery/display.js",
       "src/layers/installations/classLabel.js",
-      "src/data/cameraFraming.js"
+      "src/data/cameraFraming.js",
+      "src/app/layers/airQuality.js",
+      "src/layers/airQuality/index.js",
+      "src/layers/airQuality/model.js",
+      "src/layers/airQuality/source.js"
     ],
     "external": [
       "hls.js",
@@ -3398,7 +3406,9 @@
       "src/layers/perimeters/source.js",
       "src/layers/perimeters/records.js",
       "src/layers/submarineCables/bundledSource.js",
-      "src/layers/gnss/source.js"
+      "src/layers/gnss/source.js",
+      "src/layers/airQuality/model.js",
+      "src/layers/airQuality/source.js"
     ],
     "external": []
   },
@@ -3798,5 +3808,24 @@
       "src/data/layerStateTokenReservations.json"
     ],
     "external": []
+  },
+  "air-quality": {
+    "exports": ["./layers/air-quality"],
+    "modules": [
+      "src/layers/airQuality/index.js",
+      "src/layers/airQuality/model.js",
+      "src/layers/airQuality/source.js",
+      "src/sources/httpBody.js"
+    ],
+    "external": ["cesium"]
+  },
+  "air-quality-source": {
+    "exports": ["./layers/air-quality/source"],
+    "modules": [
+      "src/layers/airQuality/model.js",
+      "src/layers/airQuality/source.js",
+      "src/sources/httpBody.js"
+    ],
+    "external": []
   }
 }