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/workbox-precaching/precacheAndRoute.js

@@ -0,0 +1,29 @@
+/*
+  Copyright 2019 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import { addRoute } from './addRoute.js';
+import { precache } from './precache.js';
+import './_version.js';
+/**
+ * This method will add entries to the precache list and add a route to
+ * respond to fetch events.
+ *
+ * This is a convenience method that will call
+ * {@link workbox-precaching.precache} and
+ * {@link workbox-precaching.addRoute} in a single call.
+ *
+ * @param {Array<Object|string>} entries Array of entries to precache.
+ * @param {Object} [options] See the
+ * {@link workbox-precaching.PrecacheRoute} options.
+ *
+ * @memberof workbox-precaching
+ */
+function precacheAndRoute(entries, options) {
+    precache(entries);
+    addRoute(options);
+}
+export { precacheAndRoute };