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/2021/EnumerableOwnPropertyNames.js

@@ -0,0 +1,37 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var isObject = require('es-object-atoms/isObject');
+
+var objectKeys = require('object-keys');
+var safePushApply = require('safe-push-apply');
+var callBound = require('call-bound');
+
+var $isEnumerable = callBound('Object.prototype.propertyIsEnumerable');
+
+var forEach = require('../helpers/forEach');
+
+// https://262.ecma-international.org/8.0/#sec-enumerableownproperties
+
+module.exports = function EnumerableOwnPropertyNames(O, kind) {
+	if (!isObject(O)) {
+		throw new $TypeError('Assertion failed: Type(O) is not Object');
+	}
+
+	var keys = objectKeys(O);
+	if (kind === 'key') {
+		return keys;
+	}
+	if (kind === 'value' || kind === 'key+value') {
+		var results = [];
+		forEach(keys, function (key) {
+			if ($isEnumerable(O, key)) {
+				safePushApply(results, [
+					kind === 'value' ? O[key] : [key, O[key]]
+				]);
+			}
+		});
+		return results;
+	}
+	throw new $TypeError('Assertion failed: "kind" is not "key", "value", or "key+value": ' + kind);
+};