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-build/build/lib/copy-workbox-libraries.d.ts

@@ -0,0 +1,20 @@
+/**
+ * This copies over a set of runtime libraries used by Workbox into a
+ * local directory, which should be deployed alongside your service worker file.
+ *
+ * As an alternative to deploying these local copies, you could instead use
+ * Workbox from its official CDN URL.
+ *
+ * This method is exposed for the benefit of developers using
+ * {@link workbox-build.injectManifest} who would
+ * prefer not to use the CDN copies of Workbox. Developers using
+ * {@link workbox-build.generateSW} don't need to
+ * explicitly call this method.
+ *
+ * @param {string} destDirectory The path to the parent directory under which
+ * the new directory of libraries will be created.
+ * @return {Promise<string>} The name of the newly created directory.
+ *
+ * @alias workbox-build.copyWorkboxLibraries
+ */
+export declare function copyWorkboxLibraries(destDirectory: string): Promise<string>;