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/2019/StringCreate.js

@@ -0,0 +1,38 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $Object = require('es-object-atoms');
+var $StringPrototype = GetIntrinsic('%String.prototype%');
+var $SyntaxError = require('es-errors/syntax');
+var $TypeError = require('es-errors/type');
+var setProto = require('set-proto');
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+
+// https://262.ecma-international.org/6.0/#sec-stringcreate
+
+module.exports = function StringCreate(value, prototype) {
+	if (typeof value !== 'string') {
+		throw new $TypeError('Assertion failed: `S` must be a String');
+	}
+
+	var S = $Object(value);
+	if (prototype !== $StringPrototype) {
+		if (setProto) {
+			setProto(S, prototype);
+		} else {
+			throw new $SyntaxError('StringCreate: a `proto` argument that is not `String.prototype` is not supported in an environment that does not support setting the [[Prototype]]');
+		}
+	}
+
+	var length = value.length;
+	DefinePropertyOrThrow(S, 'length', {
+		'[[Configurable]]': false,
+		'[[Enumerable]]': false,
+		'[[Value]]': length,
+		'[[Writable]]': false
+	});
+
+	return S;
+};