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/compose.js

@@ -0,0 +1,55 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+exports.default = compose;
+
+var _seq = require('./seq.js');
+
+var _seq2 = _interopRequireDefault(_seq);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * Creates a function which is a composition of the passed asynchronous
+ * functions. Each function consumes the return value of the function that
+ * follows. Composing functions `f()`, `g()`, and `h()` would produce the result
+ * of `f(g(h()))`, only this version uses callbacks to obtain the return values.
+ *
+ * If the last argument to the composed function is not a function, a promise
+ * is returned when you call it.
+ *
+ * Each function is executed with the `this` binding of the composed function.
+ *
+ * @name compose
+ * @static
+ * @memberOf module:ControlFlow
+ * @method
+ * @category Control Flow
+ * @param {...AsyncFunction} functions - the asynchronous functions to compose
+ * @returns {Function} an asynchronous function that is the composed
+ * asynchronous `functions`
+ * @example
+ *
+ * function add1(n, callback) {
+ *     setTimeout(function () {
+ *         callback(null, n + 1);
+ *     }, 10);
+ * }
+ *
+ * function mul3(n, callback) {
+ *     setTimeout(function () {
+ *         callback(null, n * 3);
+ *     }, 10);
+ * }
+ *
+ * var add1mul3 = async.compose(mul3, add1);
+ * add1mul3(4, function (err, result) {
+ *     // result now equals 15
+ * });
+ */
+function compose(...args) {
+    return (0, _seq2.default)(...args.reverse());
+}
+module.exports = exports.default;