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/fast-json-stable-stringify/test/str.js

@@ -0,0 +1,46 @@
+'use strict';
+
+var test = require('tape');
+var stringify = require('../');
+
+test('simple object', function (t) {
+    t.plan(1);
+    var obj = { c: 6, b: [4,5], a: 3, z: null };
+    t.equal(stringify(obj), '{"a":3,"b":[4,5],"c":6,"z":null}');
+});
+
+test('object with undefined', function (t) {
+    t.plan(1);
+    var obj = { a: 3, z: undefined };
+    t.equal(stringify(obj), '{"a":3}');
+});
+
+test('object with null', function (t) {
+    t.plan(1);
+    var obj = { a: 3, z: null };
+    t.equal(stringify(obj), '{"a":3,"z":null}');
+});
+
+test('object with NaN and Infinity', function (t) {
+    t.plan(1);
+    var obj = { a: 3, b: NaN, c: Infinity };
+    t.equal(stringify(obj), '{"a":3,"b":null,"c":null}');
+});
+
+test('array with undefined', function (t) {
+    t.plan(1);
+    var obj = [4, undefined, 6];
+    t.equal(stringify(obj), '[4,null,6]');
+});
+
+test('object with empty string', function (t) {
+    t.plan(1);
+    var obj = { a: 3, z: '' };
+    t.equal(stringify(obj), '{"a":3,"z":""}');
+});
+
+test('array with empty string', function (t) {
+    t.plan(1);
+    var obj = [4, '', 6];
+    t.equal(stringify(obj), '[4,"",6]');
+});