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/isArrayBuffer.js

@@ -0,0 +1,27 @@
+var baseIsArrayBuffer = require('./_baseIsArrayBuffer'),
+    baseUnary = require('./_baseUnary'),
+    nodeUtil = require('./_nodeUtil');
+
+/* Node.js helper references. */
+var nodeIsArrayBuffer = nodeUtil && nodeUtil.isArrayBuffer;
+
+/**
+ * Checks if `value` is classified as an `ArrayBuffer` object.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.3.0
+ * @category Lang
+ * @param {*} value The value to check.
+ * @returns {boolean} Returns `true` if `value` is an array buffer, else `false`.
+ * @example
+ *
+ * _.isArrayBuffer(new ArrayBuffer(2));
+ * // => true
+ *
+ * _.isArrayBuffer(new Array(2));
+ * // => false
+ */
+var isArrayBuffer = nodeIsArrayBuffer ? baseUnary(nodeIsArrayBuffer) : baseIsArrayBuffer;
+
+module.exports = isArrayBuffer;