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/unsupportedIterableToArray.js

@@ -0,0 +1,9 @@
+var arrayLikeToArray = require("./arrayLikeToArray.js");
+function _unsupportedIterableToArray(r, a) {
+  if (r) {
+    if ("string" == typeof r) return arrayLikeToArray(r, a);
+    var t = {}.toString.call(r).slice(8, -1);
+    return "Object" === t && r.constructor && (t = r.constructor.name), "Map" === t || "Set" === t ? Array.from(r) : "Arguments" === t || /^(?:Ui|I)nt(?:8|16|32)(?:Clamped)?Array$/.test(t) ? arrayLikeToArray(r, a) : void 0;
+  }
+}
+module.exports = _unsupportedIterableToArray, module.exports.__esModule = true, module.exports["default"] = module.exports;