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/2020/RegExpExec.js

@@ -0,0 +1,29 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var isObject = require('es-object-atoms/isObject');
+var regexExec = require('call-bound')('RegExp.prototype.exec');
+
+var Call = require('./Call');
+var Get = require('./Get');
+var IsCallable = require('./IsCallable');
+
+// https://262.ecma-international.org/6.0/#sec-regexpexec
+
+module.exports = function RegExpExec(R, S) {
+	if (!isObject(R)) {
+		throw new $TypeError('Assertion failed: `R` must be an Object');
+	}
+	if (typeof S !== 'string') {
+		throw new $TypeError('Assertion failed: `S` must be a String');
+	}
+	var exec = Get(R, 'exec');
+	if (IsCallable(exec)) {
+		var result = Call(exec, R, [S]);
+		if (result === null || isObject(result)) {
+			return result;
+		}
+		throw new $TypeError('"exec" method must return `null` or an Object');
+	}
+	return regexExec(R, S);
+};