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/2016/GetIterator.js

@@ -0,0 +1,30 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var getIteratorMethod = require('../helpers/getIteratorMethod');
+var AdvanceStringIndex = require('./AdvanceStringIndex');
+var Call = require('./Call');
+var GetMethod = require('./GetMethod');
+
+var isObject = require('es-object-atoms/isObject');
+
+var ES = {
+	AdvanceStringIndex: AdvanceStringIndex,
+	GetMethod: GetMethod
+};
+
+// https://262.ecma-international.org/6.0/#sec-getiterator
+
+module.exports = function GetIterator(obj, method) {
+	var actualMethod = method;
+	if (arguments.length < 2) {
+		actualMethod = getIteratorMethod(ES, obj);
+	}
+	var iterator = Call(actualMethod, obj);
+	if (!isObject(iterator)) {
+		throw new $TypeError('iterator must return an object');
+	}
+
+	return iterator;
+};