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-to-primitive/index.js

@@ -0,0 +1,21 @@
+'use strict';
+
+var ES5 = require('./es5');
+var ES6 = require('./es6');
+var ES2015 = require('./es2015');
+
+if (Object.defineProperty) {
+	Object.defineProperty(ES2015, 'ES5', { enumerable: false, value: ES5 });
+	Object.defineProperty(ES2015, 'ES6', { enumerable: false, value: ES6 });
+	Object.defineProperty(ES2015, 'ES2015', { enumerable: false, value: ES2015 });
+} else {
+	// @ts-expect-error TODO
+	ES2015.ES5 = ES5;
+	// @ts-expect-error TODO
+	ES2015.ES6 = ES6;
+	// @ts-expect-error TODO
+	ES2015.ES2015 = ES2015;
+}
+
+/** @type {import('.')} */
+module.exports = ES2015;