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/fp/_convertBrowser.js

@@ -0,0 +1,18 @@
+var baseConvert = require('./_baseConvert');
+
+/**
+ * Converts `lodash` to an immutable auto-curried iteratee-first data-last
+ * version with conversion `options` applied.
+ *
+ * @param {Function} lodash The lodash function to convert.
+ * @param {Object} [options] The options object. See `baseConvert` for more details.
+ * @returns {Function} Returns the converted `lodash`.
+ */
+function browserConvert(lodash, options) {
+  return baseConvert(lodash, lodash, options);
+}
+
+if (typeof _ == 'function' && typeof _.runInContext == 'function') {
+  _ = browserConvert(_.runInContext());
+}
+module.exports = browserConvert;