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/nth.js

@@ -0,0 +1,29 @@
+var baseNth = require('./_baseNth'),
+    toInteger = require('./toInteger');
+
+/**
+ * Gets the element at index `n` of `array`. If `n` is negative, the nth
+ * element from the end is returned.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.11.0
+ * @category Array
+ * @param {Array} array The array to query.
+ * @param {number} [n=0] The index of the element to return.
+ * @returns {*} Returns the nth element of `array`.
+ * @example
+ *
+ * var array = ['a', 'b', 'c', 'd'];
+ *
+ * _.nth(array, 1);
+ * // => 'b'
+ *
+ * _.nth(array, -2);
+ * // => 'c';
+ */
+function nth(array, n) {
+  return (array && array.length) ? baseNth(array, toInteger(n)) : undefined;
+}
+
+module.exports = nth;