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/is-string/test/index.js

@@ -0,0 +1,41 @@
+'use strict';
+
+var test = require('tape');
+var isString = require('../');
+var hasToStringTag = require('has-tostringtag/shams')();
+
+test('not Strings', function (t) {
+	// @ts-expect-error
+	t.notOk(isString(), 'undefined is not String');
+	t.notOk(isString(null), 'null is not String');
+	t.notOk(isString(false), 'false is not String');
+	t.notOk(isString(true), 'true is not String');
+	t.notOk(isString([]), 'array is not String');
+	t.notOk(isString({}), 'object is not String');
+	t.notOk(isString(function () {}), 'function is not String');
+	t.notOk(isString(/a/g), 'regex literal is not String');
+	t.notOk(isString(new RegExp('a', 'g')), 'regex object is not String');
+	t.notOk(isString(new Date()), 'new Date() is not String');
+	t.notOk(isString(42), 'number is not String');
+	t.notOk(isString(Object(42)), 'number object is not String');
+	t.notOk(isString(NaN), 'NaN is not String');
+	t.notOk(isString(Infinity), 'Infinity is not String');
+	t.end();
+});
+
+test('@@toStringTag', { skip: !hasToStringTag }, function (t) {
+	/** @type {{ toString(): unknown; valueOf(): unknown; [Symbol.toStringTag]?: string; }} */
+	var fakeString = {
+		toString: function () { return '7'; },
+		valueOf: function () { return '42'; }
+	};
+	fakeString[Symbol.toStringTag] = 'String';
+	t.notOk(isString(fakeString), 'fake String with @@toStringTag "String" is not String');
+	t.end();
+});
+
+test('Strings', function (t) {
+	t.ok(isString('foo'), 'string primitive is String');
+	t.ok(isString(Object('foo')), 'string object is String');
+	t.end();
+});