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/2018/IsRegExp.js

@@ -0,0 +1,25 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $match = GetIntrinsic('%Symbol.match%', true);
+
+var hasRegExpMatcher = require('is-regex');
+var isObject = require('es-object-atoms/isObject');
+
+var ToBoolean = require('./ToBoolean');
+
+// https://262.ecma-international.org/6.0/#sec-isregexp
+
+module.exports = function IsRegExp(argument) {
+	if (!isObject(argument)) {
+		return false;
+	}
+	if ($match) {
+		var isRegExp = argument[$match];
+		if (typeof isRegExp !== 'undefined') {
+			return ToBoolean(isRegExp);
+		}
+	}
+	return hasRegExpMatcher(argument);
+};