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/2023/IsLooselyEqual.js

@@ -0,0 +1,58 @@
+'use strict';
+
+var isFinite = require('math-intrinsics/isFinite');
+var isObject = require('es-object-atoms/isObject');
+
+var IsStrictlyEqual = require('./IsStrictlyEqual');
+var StringToBigInt = require('./StringToBigInt');
+var ToNumber = require('./ToNumber');
+var ToPrimitive = require('./ToPrimitive');
+
+var isSameType = require('../helpers/isSameType');
+
+// https://262.ecma-international.org/13.0/#sec-islooselyequal
+
+module.exports = function IsLooselyEqual(x, y) {
+	if (isSameType(x, y)) {
+		return IsStrictlyEqual(x, y);
+	}
+	if (x == null && y == null) {
+		return true;
+	}
+	if (typeof x === 'number' && typeof y === 'string') {
+		return IsLooselyEqual(x, ToNumber(y));
+	}
+	if (typeof x === 'string' && typeof y === 'number') {
+		return IsLooselyEqual(ToNumber(x), y);
+	}
+	if (typeof x === 'bigint' && typeof y === 'string') {
+		var n = StringToBigInt(y);
+		if (typeof n === 'undefined') {
+			return false;
+		}
+		return IsLooselyEqual(x, n);
+	}
+	if (typeof x === 'string' && typeof y === 'bigint') {
+		return IsLooselyEqual(y, x);
+	}
+	if (typeof x === 'boolean') {
+		return IsLooselyEqual(ToNumber(x), y);
+	}
+	if (typeof y === 'boolean') {
+		return IsLooselyEqual(x, ToNumber(y));
+	}
+	if ((typeof x === 'string' || typeof x === 'number' || typeof x === 'symbol' || typeof x === 'bigint') && isObject(y)) {
+		return IsLooselyEqual(x, ToPrimitive(y));
+	}
+	if (isObject(x) && (typeof y === 'string' || typeof y === 'number' || typeof y === 'symbol' || typeof y === 'bigint')) {
+		return IsLooselyEqual(ToPrimitive(x), y);
+	}
+	if ((typeof x === 'bigint' && typeof y === 'number') || (typeof x === 'number' && typeof y === 'bigint')) {
+		if (!isFinite(x) || !isFinite(y)) {
+			return false;
+		}
+		// eslint-disable-next-line eqeqeq
+		return x == y; // shortcut for step 13.b.
+	}
+	return false;
+};