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/es-abstract/2023/GetIterator.js

@@ -0,0 +1,53 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $TypeError = require('es-errors/type');
+var $asyncIterator = GetIntrinsic('%Symbol.asyncIterator%', true);
+
+var inspect = require('object-inspect');
+var hasSymbols = require('has-symbols')();
+
+var AdvanceStringIndex = require('./AdvanceStringIndex');
+var CreateAsyncFromSyncIterator = require('./CreateAsyncFromSyncIterator');
+var GetIteratorFromMethod = require('./GetIteratorFromMethod');
+var GetMethod = require('./GetMethod');
+
+var getIteratorMethod = require('../helpers/getIteratorMethod');
+
+var ES = {
+	AdvanceStringIndex: AdvanceStringIndex,
+	GetMethod: GetMethod
+};
+
+// https://262.ecma-international.org/14.0/#sec-getiterator
+
+module.exports = function GetIterator(obj, kind) {
+	if (kind !== 'sync' && kind !== 'async') {
+		throw new $TypeError("Assertion failed: `kind` must be one of 'sync' or 'async', got " + inspect(kind));
+	}
+
+	var method;
+	if (kind === 'async') { // step 1
+		if (hasSymbols && $asyncIterator) {
+			method = GetMethod(obj, $asyncIterator); // step 1.a
+		}
+	}
+	if (typeof method === 'undefined') { // step 1.b
+		// var syncMethod = GetMethod(obj, $iterator); // step 1.b.i
+		var syncMethod = getIteratorMethod(ES, obj);
+		if (kind === 'async') {
+			if (typeof syncMethod === 'undefined') {
+				throw new $TypeError('iterator method is `undefined`'); // step 1.b.ii
+			}
+			var syncIteratorRecord = GetIteratorFromMethod(obj, syncMethod); // step 1.b.iii
+			return CreateAsyncFromSyncIterator(syncIteratorRecord); // step 1.b.iv
+		}
+		method = syncMethod; // step 2, kind of
+	}
+
+	if (typeof method === 'undefined') {
+		throw new $TypeError('iterator method is `undefined`'); // step 3
+	}
+	return GetIteratorFromMethod(obj, method); // step 4
+};