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-deep-equal/index.js

@@ -0,0 +1,46 @@
+'use strict';
+
+// do not edit .js files directly - edit src/index.jst
+
+
+
+module.exports = function equal(a, b) {
+  if (a === b) return true;
+
+  if (a && b && typeof a == 'object' && typeof b == 'object') {
+    if (a.constructor !== b.constructor) return false;
+
+    var length, i, keys;
+    if (Array.isArray(a)) {
+      length = a.length;
+      if (length != b.length) return false;
+      for (i = length; i-- !== 0;)
+        if (!equal(a[i], b[i])) return false;
+      return true;
+    }
+
+
+
+    if (a.constructor === RegExp) return a.source === b.source && a.flags === b.flags;
+    if (a.valueOf !== Object.prototype.valueOf) return a.valueOf() === b.valueOf();
+    if (a.toString !== Object.prototype.toString) return a.toString() === b.toString();
+
+    keys = Object.keys(a);
+    length = keys.length;
+    if (length !== Object.keys(b).length) return false;
+
+    for (i = length; i-- !== 0;)
+      if (!Object.prototype.hasOwnProperty.call(b, keys[i])) return false;
+
+    for (i = length; i-- !== 0;) {
+      var key = keys[i];
+
+      if (!equal(a[key], b[key])) return false;
+    }
+
+    return true;
+  }
+
+  // true if both NaN, false otherwise
+  return a!==a && b!==b;
+};