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/@vitest/mocker/dist/register.d.ts

@@ -0,0 +1,8 @@
+import { M as ModuleMockerInterceptor, a as ModuleMockerCompilerHints, b as ModuleMocker } from './mocker-pQgp1HFr.js';
+import '@vitest/spy';
+import './types-DZOqTgiN.js';
+
+declare function registerModuleMocker(interceptor: (accessor: string) => ModuleMockerInterceptor): ModuleMockerCompilerHints;
+declare function registerNativeFactoryResolver(mocker: ModuleMocker): void;
+
+export { registerModuleMocker, registerNativeFactoryResolver };