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/_memoizeCapped.js

@@ -0,0 +1,26 @@
+var memoize = require('./memoize');
+
+/** Used as the maximum memoize cache size. */
+var MAX_MEMOIZE_SIZE = 500;
+
+/**
+ * A specialized version of `_.memoize` which clears the memoized function's
+ * cache when it exceeds `MAX_MEMOIZE_SIZE`.
+ *
+ * @private
+ * @param {Function} func The function to have its output memoized.
+ * @returns {Function} Returns the new memoized function.
+ */
+function memoizeCapped(func) {
+  var result = memoize(func, function(key) {
+    if (cache.size === MAX_MEMOIZE_SIZE) {
+      cache.clear();
+    }
+    return key;
+  });
+
+  var cache = result.cache;
+  return result;
+}
+
+module.exports = memoizeCapped;