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/which-boxed-primitive/index.js

@@ -0,0 +1,31 @@
+'use strict';
+
+var isString = require('is-string');
+var isNumber = require('is-number-object');
+var isBoolean = require('is-boolean-object');
+var isSymbol = require('is-symbol');
+var isBigInt = require('is-bigint');
+
+/** @type {import('.')} */
+// eslint-disable-next-line consistent-return
+module.exports = function whichBoxedPrimitive(value) {
+	// eslint-disable-next-line eqeqeq
+	if (value == null || (typeof value !== 'object' && typeof value !== 'function')) {
+		return null;
+	}
+	if (isString(value)) {
+		return 'String';
+	}
+	if (isNumber(value)) {
+		return 'Number';
+	}
+	if (isBoolean(value)) {
+		return 'Boolean';
+	}
+	if (isSymbol(value)) {
+		return 'Symbol';
+	}
+	if (isBigInt(value)) {
+		return 'BigInt';
+	}
+};