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/es5.js

@@ -0,0 +1,52 @@
+'use strict';
+
+var toStr = Object.prototype.toString;
+
+var isPrimitive = require('./helpers/isPrimitive');
+
+var isCallable = require('is-callable');
+
+/** @type {{ [k in `[[${string}]]`]: (O: { toString?: unknown, valueOf?: unknown }, actualHint?: StringConstructor | NumberConstructor) => null | undefined | string | symbol | number | boolean | bigint; }} */
+// http://ecma-international.org/ecma-262/5.1/#sec-8.12.8
+var ES5internalSlots = {
+	'[[DefaultValue]]': function (O) {
+		var actualHint;
+		if (arguments.length > 1) {
+			actualHint = arguments[1];
+		} else {
+			actualHint = toStr.call(O) === '[object Date]' ? String : Number;
+		}
+
+		if (actualHint === String || actualHint === Number) {
+			/** @type {('toString' | 'valueOf')[]} */
+			var methods = actualHint === String ? ['toString', 'valueOf'] : ['valueOf', 'toString'];
+			var value, i;
+			for (i = 0; i < methods.length; ++i) {
+				var method = methods[i];
+				if (isCallable(O[method])) {
+					// eslint-disable-next-line no-extra-parens
+					value = /** @type {Function} */ (O[method])();
+					if (isPrimitive(value)) {
+						return value;
+					}
+				}
+			}
+			throw new TypeError('No default value');
+		}
+		throw new TypeError('invalid [[DefaultValue]] hint supplied');
+	}
+};
+
+/** @type {import('./es5')} */
+// http://ecma-international.org/ecma-262/5.1/#sec-9.1
+module.exports = function ToPrimitive(input) {
+	if (isPrimitive(input)) {
+		return input;
+	}
+	if (arguments.length > 1) {
+		// eslint-disable-next-line no-extra-parens
+		return ES5internalSlots['[[DefaultValue]]'](/** @type {object} */ (input), arguments[1]);
+	}
+	// eslint-disable-next-line no-extra-parens
+	return ES5internalSlots['[[DefaultValue]]'](/** @type {object} */ (input));
+};