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/_baseKeysIn.js

@@ -0,0 +1,33 @@
+var isObject = require('./isObject'),
+    isPrototype = require('./_isPrototype'),
+    nativeKeysIn = require('./_nativeKeysIn');
+
+/** Used for built-in method references. */
+var objectProto = Object.prototype;
+
+/** Used to check objects for own properties. */
+var hasOwnProperty = objectProto.hasOwnProperty;
+
+/**
+ * The base implementation of `_.keysIn` which doesn't treat sparse arrays as dense.
+ *
+ * @private
+ * @param {Object} object The object to query.
+ * @returns {Array} Returns the array of property names.
+ */
+function baseKeysIn(object) {
+  if (!isObject(object)) {
+    return nativeKeysIn(object);
+  }
+  var isProto = isPrototype(object),
+      result = [];
+
+  for (var key in object) {
+    if (!(key == 'constructor' && (isProto || !hasOwnProperty.call(object, key)))) {
+      result.push(key);
+    }
+  }
+  return result;
+}
+
+module.exports = baseKeysIn;