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/toIterator.js

@@ -0,0 +1,23 @@
+/**
+ * Enables the wrapper to be iterable.
+ *
+ * @name Symbol.iterator
+ * @memberOf _
+ * @since 4.0.0
+ * @category Seq
+ * @returns {Object} Returns the wrapper object.
+ * @example
+ *
+ * var wrapped = _([1, 2]);
+ *
+ * wrapped[Symbol.iterator]() === wrapped;
+ * // => true
+ *
+ * Array.from(wrapped);
+ * // => [1, 2]
+ */
+function wrapperToIterator() {
+  return this;
+}
+
+module.exports = wrapperToIterator;