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/has-symbols/test/shams/get-own-property-symbols.js

@@ -0,0 +1,29 @@
+'use strict';
+
+var test = require('tape');
+
+if (typeof Symbol === 'function' && typeof Symbol() === 'symbol') {
+	test('has native Symbol support', function (t) {
+		t.equal(typeof Symbol, 'function');
+		t.equal(typeof Symbol(), 'symbol');
+		t.end();
+	});
+	// @ts-expect-error TS is stupid and doesn't know about top level return
+	return;
+}
+
+var hasSymbols = require('../../shams');
+
+test('polyfilled Symbols', function (t) {
+	/* eslint-disable global-require */
+	t.equal(hasSymbols(), false, 'hasSymbols is false before polyfilling');
+
+	require('get-own-property-symbols');
+
+	require('../tests')(t);
+
+	var hasSymbolsAfter = hasSymbols();
+	t.equal(hasSymbolsAfter, true, 'hasSymbols is true after polyfilling');
+	/* eslint-enable global-require */
+	t.end();
+});