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/sortedUniqBy.js

@@ -0,0 +1,26 @@
+var baseIteratee = require('./_baseIteratee'),
+    baseSortedUniq = require('./_baseSortedUniq');
+
+/**
+ * This method is like `_.uniqBy` except that it's designed and optimized
+ * for sorted arrays.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Array
+ * @param {Array} array The array to inspect.
+ * @param {Function} [iteratee] The iteratee invoked per element.
+ * @returns {Array} Returns the new duplicate free array.
+ * @example
+ *
+ * _.sortedUniqBy([1.1, 1.2, 2.3, 2.4], Math.floor);
+ * // => [1.1, 2.3]
+ */
+function sortedUniqBy(array, iteratee) {
+  return (array && array.length)
+    ? baseSortedUniq(array, baseIteratee(iteratee, 2))
+    : [];
+}
+
+module.exports = sortedUniqBy;