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/_arrayReduceRight.js

@@ -0,0 +1,24 @@
+/**
+ * A specialized version of `_.reduceRight` for arrays without support for
+ * iteratee shorthands.
+ *
+ * @private
+ * @param {Array} [array] The array to iterate over.
+ * @param {Function} iteratee The function invoked per iteration.
+ * @param {*} [accumulator] The initial value.
+ * @param {boolean} [initAccum] Specify using the last element of `array` as
+ *  the initial value.
+ * @returns {*} Returns the accumulated value.
+ */
+function arrayReduceRight(array, iteratee, accumulator, initAccum) {
+  var length = array == null ? 0 : array.length;
+  if (initAccum && length) {
+    accumulator = array[--length];
+  }
+  while (length--) {
+    accumulator = iteratee(accumulator, array[length], length, array);
+  }
+  return accumulator;
+}
+
+module.exports = arrayReduceRight;