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/_baseSortedUniq.js

@@ -0,0 +1,30 @@
+var eq = require('./eq');
+
+/**
+ * The base implementation of `_.sortedUniq` and `_.sortedUniqBy` without
+ * support for iteratee shorthands.
+ *
+ * @private
+ * @param {Array} array The array to inspect.
+ * @param {Function} [iteratee] The iteratee invoked per element.
+ * @returns {Array} Returns the new duplicate free array.
+ */
+function baseSortedUniq(array, iteratee) {
+  var index = -1,
+      length = array.length,
+      resIndex = 0,
+      result = [];
+
+  while (++index < length) {
+    var value = array[index],
+        computed = iteratee ? iteratee(value) : value;
+
+    if (!index || !eq(computed, seen)) {
+      var seen = computed;
+      result[resIndex++] = value === 0 ? 0 : value;
+    }
+  }
+  return result;
+}
+
+module.exports = baseSortedUniq;