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/nthArg.js

@@ -0,0 +1,32 @@
+var baseNth = require('./_baseNth'),
+    baseRest = require('./_baseRest'),
+    toInteger = require('./toInteger');
+
+/**
+ * Creates a function that gets the argument at index `n`. If `n` is negative,
+ * the nth argument from the end is returned.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Util
+ * @param {number} [n=0] The index of the argument to return.
+ * @returns {Function} Returns the new pass-thru function.
+ * @example
+ *
+ * var func = _.nthArg(1);
+ * func('a', 'b', 'c', 'd');
+ * // => 'b'
+ *
+ * var func = _.nthArg(-2);
+ * func('a', 'b', 'c', 'd');
+ * // => 'c'
+ */
+function nthArg(n) {
+  n = toInteger(n);
+  return baseRest(function(args) {
+    return baseNth(args, n);
+  });
+}
+
+module.exports = nthArg;