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/_baseAt.js

@@ -0,0 +1,23 @@
+var get = require('./get');
+
+/**
+ * The base implementation of `_.at` without support for individual paths.
+ *
+ * @private
+ * @param {Object} object The object to iterate over.
+ * @param {string[]} paths The property paths to pick.
+ * @returns {Array} Returns the picked elements.
+ */
+function baseAt(object, paths) {
+  var index = -1,
+      length = paths.length,
+      result = Array(length),
+      skip = object == null;
+
+  while (++index < length) {
+    result[index] = skip ? undefined : get(object, paths[index]);
+  }
+  return result;
+}
+
+module.exports = baseAt;