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/at.js

@@ -0,0 +1,23 @@
+var baseAt = require('./_baseAt'),
+    flatRest = require('./_flatRest');
+
+/**
+ * Creates an array of values corresponding to `paths` of `object`.
+ *
+ * @static
+ * @memberOf _
+ * @since 1.0.0
+ * @category Object
+ * @param {Object} object The object to iterate over.
+ * @param {...(string|string[])} [paths] The property paths to pick.
+ * @returns {Array} Returns the picked values.
+ * @example
+ *
+ * var object = { 'a': [{ 'b': { 'c': 3 } }, 4] };
+ *
+ * _.at(object, ['a[0].b.c', 'a[1]']);
+ * // => [3, 4]
+ */
+var at = flatRest(baseAt);
+
+module.exports = at;