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/_baseTrim.js

@@ -0,0 +1,19 @@
+var trimmedEndIndex = require('./_trimmedEndIndex');
+
+/** Used to match leading whitespace. */
+var reTrimStart = /^\s+/;
+
+/**
+ * The base implementation of `_.trim`.
+ *
+ * @private
+ * @param {string} string The string to trim.
+ * @returns {string} Returns the trimmed string.
+ */
+function baseTrim(string) {
+  return string
+    ? string.slice(0, trimmedEndIndex(string) + 1).replace(reTrimStart, '')
+    : string;
+}
+
+module.exports = baseTrim;