Merge upstream/main: cockpit emergency, GNSS integrity and GeoJSON import meet i18n

Upstream advanced past the KartaView merge: transponder-emergency HUD
wording (formatCockpitEmergency in cockpitMath), the GNSS integrity
layer joined the Events group, and a GeoJSON/KML/KMZ/GPX file-import
control landed - all in regions this branch localizes.

- cockpitMath: upstream's formatCockpitEmergency kept alongside the
  branch's formatter-injected Context scope (module stays i18n-free;
  squawk/ADS-B codes and the broadcast label are data).
- cockpitInstruments: the emergency HUD line composed with t()
  placeholders; fleet/feedState stay translated, the 'emergency' class
  toggle kept.
- layerPanel: upstream's gnss-integrity id with msg('Events').
- package-boundaries: both sides' entries unioned.
- New upstream UI strings marked and translated, as the branch's
  unmarked-string detector requires: the geo-import control's markup
  (data-i18n-title/-aria-label/text), its list titles, hints and
  summarize() lines (t/tn with placeholders), the aircraft emergency
  labels (msg data), and the GNSS legend blurb (t with placeholders).
- es/ru catalogs: 26 new keys each (2019 messages).

npm run i18n: complete, no unmarked strings. npm test: 6739/6741 (the
one failure is the pre-existing environmental OPENAI_API_KEY leak in
devFreshDotenv). Build passes.

package.json

@@ -166,6 +166,7 @@
     "./layers/recent-imagery": "./src/layers/recentImagery/index.js",
     "./layers/recent-imagery/source": "./src/layers/recentImagery/source.js",
     "./layers/perimeters": "./src/layers/perimeters/index.js",
+    "./layers/gnss": "./src/layers/gnss/index.js",
     "./sources/firms-csv": "./src/data/firmsCsv.js",
     "./layers/firms": "./src/layers/firms/index.js",
     "./layers/satellites": "./src/layers/satellites/index.js",
@@ -239,6 +240,7 @@
     "./layers/cctv/source": "./src/layers/cctv/source.js",
     "./layers/earthquakes/source": "./src/layers/earthquakes/source.js",
     "./layers/perimeters/source": "./src/layers/perimeters/source.js",
+    "./layers/gnss/source": "./src/layers/gnss/source.js",
     "./layers/firms/source": "./src/layers/firms/source.js",
     "./layers/installations/source": "./src/layers/installations/source.js",
     "./layers/launches/source": "./src/layers/launches/source.js",