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/additional-manifest-entries-transform.d.ts

@@ -0,0 +1,13 @@
+import { ManifestEntry } from '../types';
+type AdditionalManifestEntriesTransform = {
+    (manifest: Array<ManifestEntry & {
+        size: number;
+    }>): {
+        manifest: Array<ManifestEntry & {
+            size: number;
+        }>;
+        warnings: string[];
+    };
+};
+export declare function additionalManifestEntriesTransform(additionalManifestEntries: Array<ManifestEntry | string>): AdditionalManifestEntriesTransform;
+export {};