Add progressive web app companion for cross-platform access

Vite + TypeScript PWA that mirrors the Android app's core features:
- Pre-processed shelter data (build-time UTM33N→WGS84 conversion)
- Leaflet map with shelter markers, user location, and offline tiles
- Canvas compass arrow (ported from DirectionArrowView.kt)
- IndexedDB shelter cache with 7-day staleness check
- Service worker with CacheFirst tiles and precached app shell
- i18n for en, nb, nn (ported from Android strings.xml)
- iOS/Android compass handling with low-pass filter
- Respects user map interaction (no auto-snap on pan/zoom)
- Build revision cache-breaker for reliable SW updates

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

pwa/node_modules/@babel/runtime/helpers/esm/regeneratorKeys.js

@@ -0,0 +1,10 @@
+function _regeneratorKeys(e) {
+  var n = Object(e),
+    r = [];
+  for (var t in n) r.unshift(t);
+  return function e() {
+    for (; r.length;) if ((t = r.pop()) in n) return e.value = t, e.done = !1, e;
+    return e.done = !0, e;
+  };
+}
+export { _regeneratorKeys as default };