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/CompareArrayElements.js

@@ -0,0 +1,50 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var Call = require('./Call');
+var IsLessThan = require('./IsLessThan');
+var ToNumber = require('./ToNumber');
+var ToString = require('./ToString');
+
+var isNaN = require('math-intrinsics/isNaN');
+
+// https://262.ecma-international.org/14.0/#sec-comparearrayelements
+
+module.exports = function CompareArrayElements(x, y, compareFn) {
+	if (typeof compareFn !== 'function' && typeof compareFn !== 'undefined') {
+		throw new $TypeError('Assertion failed: `compareFn` must be a function or undefined');
+	}
+
+	if (typeof x === 'undefined' && typeof y === 'undefined') {
+		return 0; // step 1
+	}
+
+	if (typeof x === 'undefined') {
+		return 1; // step 2
+	}
+
+	if (typeof y === 'undefined') {
+		return -1; // step 3
+	}
+
+	if (typeof compareFn !== 'undefined') { // step 4
+		var v = ToNumber(Call(compareFn, void undefined, [x, y])); // step 4.a
+		if (isNaN(v)) {
+			return 0; // step 4.b
+		}
+		return v; // step 4.c
+	}
+
+	var xString = ToString(x); // step 5
+	var yString = ToString(y); // step 6
+	var xSmaller = IsLessThan(xString, yString, true); // step 7
+	if (xSmaller) {
+		return -1; // step 8
+	}
+	var ySmaller = IsLessThan(yString, xString, true); // step 9
+	if (ySmaller) {
+		return 1; // step 10
+	}
+	return 0; // step 11
+};