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/merge.js

@@ -0,0 +1,39 @@
+var baseMerge = require('./_baseMerge'),
+    createAssigner = require('./_createAssigner');
+
+/**
+ * This method is like `_.assign` except that it recursively merges own and
+ * inherited enumerable string keyed properties of source objects into the
+ * destination object. Source properties that resolve to `undefined` are
+ * skipped if a destination value exists. Array and plain object properties
+ * are merged recursively. Other objects and value types are overridden by
+ * assignment. Source objects are applied from left to right. Subsequent
+ * sources overwrite property assignments of previous sources.
+ *
+ * **Note:** This method mutates `object`.
+ *
+ * @static
+ * @memberOf _
+ * @since 0.5.0
+ * @category Object
+ * @param {Object} object The destination object.
+ * @param {...Object} [sources] The source objects.
+ * @returns {Object} Returns `object`.
+ * @example
+ *
+ * var object = {
+ *   'a': [{ 'b': 2 }, { 'd': 4 }]
+ * };
+ *
+ * var other = {
+ *   'a': [{ 'c': 3 }, { 'e': 5 }]
+ * };
+ *
+ * _.merge(object, other);
+ * // => { 'a': [{ 'b': 2, 'c': 3 }, { 'd': 4, 'e': 5 }] }
+ */
+var merge = createAssigner(function(object, source, srcIndex) {
+  baseMerge(object, source, srcIndex);
+});
+
+module.exports = merge;