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/toLower.js

@@ -0,0 +1,28 @@
+var toString = require('./toString');
+
+/**
+ * Converts `string`, as a whole, to lower case just like
+ * [String#toLowerCase](https://mdn.io/toLowerCase).
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category String
+ * @param {string} [string=''] The string to convert.
+ * @returns {string} Returns the lower cased string.
+ * @example
+ *
+ * _.toLower('--Foo-Bar--');
+ * // => '--foo-bar--'
+ *
+ * _.toLower('fooBar');
+ * // => 'foobar'
+ *
+ * _.toLower('__FOO_BAR__');
+ * // => '__foo_bar__'
+ */
+function toLower(value) {
+  return toString(value).toLowerCase();
+}
+
+module.exports = toLower;