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/unbox-primitive/index.js

@@ -0,0 +1,42 @@
+'use strict';
+
+var whichBoxedPrimitive = require('which-boxed-primitive');
+var callBound = require('call-bound');
+var hasSymbols = require('has-symbols')();
+var hasBigInts = require('has-bigints')();
+
+var stringToString = callBound('String.prototype.toString');
+var numberValueOf = callBound('Number.prototype.valueOf');
+var booleanValueOf = callBound('Boolean.prototype.valueOf');
+var symbolValueOf = hasSymbols && callBound('Symbol.prototype.valueOf');
+var bigIntValueOf = hasBigInts && callBound('BigInt.prototype.valueOf');
+
+/** @type {import('.')} */
+module.exports = function unboxPrimitive(value) {
+	var which = whichBoxedPrimitive(value);
+	if (typeof which !== 'string') {
+		throw new TypeError(which === null ? 'value is an unboxed primitive' : 'value is a non-boxed-primitive object');
+	}
+
+	if (which === 'String') {
+		return stringToString(value);
+	}
+	if (which === 'Number') {
+		return numberValueOf(value);
+	}
+	if (which === 'Boolean') {
+		return booleanValueOf(value);
+	}
+	if (which === 'Symbol') {
+		if (!hasSymbols) {
+			throw new EvalError('somehow this environment does not have Symbols, but you have a boxed Symbol value. Please report this!');
+		}
+		// eslint-disable-next-line no-extra-parens
+		return /** @type {Exclude<typeof symbolValueOf, false>} */ (symbolValueOf)(value);
+	}
+	if (which === 'BigInt') {
+		// eslint-disable-next-line no-extra-parens
+		return /** @type {Exclude<typeof bigIntValueOf, false>} */ (bigIntValueOf)(value);
+	}
+	throw new RangeError('unknown boxed primitive found: ' + which);
+};