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/_createAggregator.js

@@ -0,0 +1,23 @@
+var arrayAggregator = require('./_arrayAggregator'),
+    baseAggregator = require('./_baseAggregator'),
+    baseIteratee = require('./_baseIteratee'),
+    isArray = require('./isArray');
+
+/**
+ * Creates a function like `_.groupBy`.
+ *
+ * @private
+ * @param {Function} setter The function to set accumulator values.
+ * @param {Function} [initializer] The accumulator object initializer.
+ * @returns {Function} Returns the new aggregator function.
+ */
+function createAggregator(setter, initializer) {
+  return function(collection, iteratee) {
+    var func = isArray(collection) ? arrayAggregator : baseAggregator,
+        accumulator = initializer ? initializer() : {};
+
+    return func(collection, setter, baseIteratee(iteratee, 2), accumulator);
+  };
+}
+
+module.exports = createAggregator;