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/object.assign/test/implementation.js

@@ -0,0 +1,19 @@
+'use strict';
+
+var implementation = require('../implementation');
+var callBind = require('call-bind');
+var test = require('tape');
+var hasStrictMode = require('has-strict-mode')();
+var runTests = require('./tests');
+
+test('as a function', function (t) {
+	t.test('bad first arg/receiver', { skip: !hasStrictMode }, function (st) {
+		st['throws'](function () { implementation(undefined); }, TypeError, 'undefined is not an object');
+		st['throws'](function () { implementation(null); }, TypeError, 'null is not an object');
+		st.end();
+	});
+
+	runTests(callBind(implementation, Object), t);
+
+	t.end();
+});