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/lodash/_stringToPath.js

@@ -0,0 +1,27 @@
+var memoizeCapped = require('./_memoizeCapped');
+
+/** Used to match property names within property paths. */
+var rePropName = /[^.[\]]+|\[(?:(-?\d+(?:\.\d+)?)|(["'])((?:(?!\2)[^\\]|\\.)*?)\2)\]|(?=(?:\.|\[\])(?:\.|\[\]|$))/g;
+
+/** Used to match backslashes in property paths. */
+var reEscapeChar = /\\(\\)?/g;
+
+/**
+ * Converts `string` to a property path array.
+ *
+ * @private
+ * @param {string} string The string to convert.
+ * @returns {Array} Returns the property path array.
+ */
+var stringToPath = memoizeCapped(function(string) {
+  var result = [];
+  if (string.charCodeAt(0) === 46 /* . */) {
+    result.push('');
+  }
+  string.replace(rePropName, function(match, number, quote, subString) {
+    result.push(quote ? subString.replace(reEscapeChar, '$1') : (number || match));
+  });
+  return result;
+});
+
+module.exports = stringToPath;