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/2022/CharacterRange.js

@@ -0,0 +1,53 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+var callBound = require('call-bound');
+
+var $fromCharCode = GetIntrinsic('%String.fromCharCode%');
+var $TypeError = require('es-errors/type');
+var $charCodeAt = callBound('String.prototype.charCodeAt');
+
+var CharSet = require('../helpers/CharSet').CharSet;
+
+module.exports = function CharacterRange(A, B) {
+	var a;
+	var b;
+
+	if (A instanceof CharSet || B instanceof CharSet) {
+		if (!(A instanceof CharSet) || !(B instanceof CharSet)) {
+			throw new $TypeError('Assertion failed: CharSets A and B are not both CharSets');
+		}
+
+		A.yield(function (c) {
+			if (typeof a !== 'undefined') {
+				throw new $TypeError('Assertion failed: CharSet A has more than one character');
+			}
+			a = c;
+		});
+		B.yield(function (c) {
+			if (typeof b !== 'undefined') {
+				throw new $TypeError('Assertion failed: CharSet B has more than one character');
+			}
+			b = c;
+		});
+	} else {
+		if (A.length !== 1 || B.length !== 1) {
+			throw new $TypeError('Assertion failed: CharSets A and B contain exactly one character');
+		}
+		a = A[0];
+		b = B[0];
+	}
+
+	var i = $charCodeAt(a, 0);
+	var j = $charCodeAt(b, 0);
+
+	if (!(i <= j)) {
+		throw new $TypeError('Assertion failed: i is not <= j');
+	}
+
+	var arr = [];
+	for (var k = i; k <= j; k += 1) {
+		arr[arr.length] = $fromCharCode(k);
+	}
+	return arr;
+};