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/createHandlerBoundToURL.d.ts

@@ -0,0 +1,21 @@
+import { RouteHandlerCallback } from 'workbox-core/types.js';
+import './_version.js';
+/**
+ * Helper function that calls
+ * {@link PrecacheController#createHandlerBoundToURL} on the default
+ * {@link PrecacheController} instance.
+ *
+ * If you are creating your own {@link PrecacheController}, then call the
+ * {@link PrecacheController#createHandlerBoundToURL} on that instance,
+ * instead of using this function.
+ *
+ * @param {string} url The precached URL which will be used to lookup the
+ * `Response`.
+ * @param {boolean} [fallbackToNetwork=true] Whether to attempt to get the
+ * response from the network if there's a precache miss.
+ * @return {workbox-routing~handlerCallback}
+ *
+ * @memberof workbox-precaching
+ */
+declare function createHandlerBoundToURL(url: string): RouteHandlerCallback;
+export { createHandlerBoundToURL };