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/async/setImmediate.js

@@ -0,0 +1,45 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+
+var _setImmediate = require('./internal/setImmediate.js');
+
+var _setImmediate2 = _interopRequireDefault(_setImmediate);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * Calls `callback` on a later loop around the event loop. In Node.js this just
+ * calls `setImmediate`.  In the browser it will use `setImmediate` if
+ * available, otherwise `setTimeout(callback, 0)`, which means other higher
+ * priority events may precede the execution of `callback`.
+ *
+ * This is used internally for browser-compatibility purposes.
+ *
+ * @name setImmediate
+ * @static
+ * @memberOf module:Utils
+ * @method
+ * @see [async.nextTick]{@link module:Utils.nextTick}
+ * @category Util
+ * @param {Function} callback - The function to call on a later loop around
+ * the event loop. Invoked with (args...).
+ * @param {...*} args... - any number of additional arguments to pass to the
+ * callback on the next tick.
+ * @example
+ *
+ * var call_order = [];
+ * async.nextTick(function() {
+ *     call_order.push('two');
+ *     // call_order now equals ['one','two']
+ * });
+ * call_order.push('one');
+ *
+ * async.setImmediate(function (a, b, c) {
+ *     // a, b, and c equal 1, 2, and 3
+ * }, 1, 2, 3);
+ */
+exports.default = _setImmediate2.default;
+module.exports = exports.default;