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/objectSpread.js

@@ -0,0 +1,14 @@
+import defineProperty from "./defineProperty.js";
+function _objectSpread(e) {
+  for (var r = 1; r < arguments.length; r++) {
+    var t = null != arguments[r] ? Object(arguments[r]) : {},
+      o = Object.keys(t);
+    "function" == typeof Object.getOwnPropertySymbols && o.push.apply(o, Object.getOwnPropertySymbols(t).filter(function (e) {
+      return Object.getOwnPropertyDescriptor(t, e).enumerable;
+    })), o.forEach(function (r) {
+      defineProperty(e, r, t[r]);
+    });
+  }
+  return e;
+}
+export { _objectSpread as default };