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/async/internal/iterator.js

@@ -0,0 +1,57 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = createIterator;
+
+var _isArrayLike = require('./isArrayLike.js');
+
+var _isArrayLike2 = _interopRequireDefault(_isArrayLike);
+
+var _getIterator = require('./getIterator.js');
+
+var _getIterator2 = _interopRequireDefault(_getIterator);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+function createArrayIterator(coll) {
+    var i = -1;
+    var len = coll.length;
+    return function next() {
+        return ++i < len ? { value: coll[i], key: i } : null;
+    };
+}
+
+function createES2015Iterator(iterator) {
+    var i = -1;
+    return function next() {
+        var item = iterator.next();
+        if (item.done) return null;
+        i++;
+        return { value: item.value, key: i };
+    };
+}
+
+function createObjectIterator(obj) {
+    var okeys = obj ? Object.keys(obj) : [];
+    var i = -1;
+    var len = okeys.length;
+    return function next() {
+        var key = okeys[++i];
+        if (key === '__proto__') {
+            return next();
+        }
+        return i < len ? { value: obj[key], key } : null;
+    };
+}
+
+function createIterator(coll) {
+    if ((0, _isArrayLike2.default)(coll)) {
+        return createArrayIterator(coll);
+    }
+
+    var iterator = (0, _getIterator2.default)(coll);
+    return iterator ? createES2015Iterator(iterator) : createObjectIterator(coll);
+}
+module.exports = exports.default;