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/2025/GetMatchIndexPair.js

@@ -0,0 +1,24 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var isMatchRecord = require('../helpers/records/match-record');
+
+// https://262.ecma-international.org/13.0/#sec-getmatchindexpair
+
+module.exports = function GetMatchIndexPair(S, match) {
+	if (typeof S !== 'string') {
+		throw new $TypeError('Assertion failed: `S` must be a String');
+	}
+	if (!isMatchRecord(match)) {
+		throw new $TypeError('Assertion failed: `match` must be a Match Record');
+	}
+
+	if (!(match['[[StartIndex]]'] <= S.length)) {
+		throw new $TypeError('`match` [[StartIndex]] must be a non-negative integer <= the length of S');
+	}
+	if (!(match['[[EndIndex]]'] <= S.length)) {
+		throw new $TypeError('`match` [[EndIndex]] must be an integer between [[StartIndex]] and the length of S, inclusive');
+	}
+	return [match['[[StartIndex]]'], match['[[EndIndex]]']];
+};