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/2018/OrdinaryToPrimitive.js

@@ -0,0 +1,36 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var isObject = require('es-object-atoms/isObject');
+
+var Call = require('./Call');
+var Get = require('./Get');
+var IsCallable = require('./IsCallable');
+
+var inspect = require('object-inspect');
+
+// https://262.ecma-international.org/8.0/#sec-ordinarytoprimitive
+
+module.exports = function OrdinaryToPrimitive(O, hint) {
+	if (!isObject(O)) {
+		throw new $TypeError('Assertion failed: Type(O) is not Object');
+	}
+	if (/* typeof hint !== 'string' || */ hint !== 'string' && hint !== 'number') {
+		throw new $TypeError('Assertion failed: `hint` must be "string" or "number"');
+	}
+
+	var methodNames = hint === 'string' ? ['toString', 'valueOf'] : ['valueOf', 'toString'];
+
+	for (var i = 0; i < methodNames.length; i += 1) {
+		var name = methodNames[i];
+		var method = Get(O, name);
+		if (IsCallable(method)) {
+			var result = Call(method, O);
+			if (!isObject(result)) {
+				return result;
+			}
+		}
+	}
+
+	throw new $TypeError('No primitive value for ' + inspect(O));
+};