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/join.js

@@ -0,0 +1,26 @@
+/** Used for built-in method references. */
+var arrayProto = Array.prototype;
+
+/* Built-in method references for those with the same name as other `lodash` methods. */
+var nativeJoin = arrayProto.join;
+
+/**
+ * Converts all elements in `array` into a string separated by `separator`.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Array
+ * @param {Array} array The array to convert.
+ * @param {string} [separator=','] The element separator.
+ * @returns {string} Returns the joined string.
+ * @example
+ *
+ * _.join(['a', 'b', 'c'], '~');
+ * // => 'a~b~c'
+ */
+function join(array, separator) {
+  return array == null ? '' : nativeJoin.call(array, separator);
+}
+
+module.exports = join;