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/priorityQueue.js

@@ -0,0 +1,60 @@
+'use strict';
+
+Object.defineProperty(exports, "__esModule", {
+    value: true
+});
+
+exports.default = function (worker, concurrency) {
+    // Start with a normal queue
+    var q = (0, _queue2.default)(worker, concurrency);
+
+    var {
+        push,
+        pushAsync
+    } = q;
+
+    q._tasks = new _Heap2.default();
+    q._createTaskItem = ({ data, priority }, callback) => {
+        return {
+            data,
+            priority,
+            callback
+        };
+    };
+
+    function createDataItems(tasks, priority) {
+        if (!Array.isArray(tasks)) {
+            return { data: tasks, priority };
+        }
+        return tasks.map(data => {
+            return { data, priority };
+        });
+    }
+
+    // Override push to accept second parameter representing priority
+    q.push = function (data, priority = 0, callback) {
+        return push(createDataItems(data, priority), callback);
+    };
+
+    q.pushAsync = function (data, priority = 0, callback) {
+        return pushAsync(createDataItems(data, priority), callback);
+    };
+
+    // Remove unshift functions
+    delete q.unshift;
+    delete q.unshiftAsync;
+
+    return q;
+};
+
+var _queue = require('./queue.js');
+
+var _queue2 = _interopRequireDefault(_queue);
+
+var _Heap = require('./internal/Heap.js');
+
+var _Heap2 = _interopRequireDefault(_Heap);
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+module.exports = exports.default;