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/balanced-match/dist/esm/index.d.ts

@@ -0,0 +1,9 @@
+export declare const balanced: (a: string | RegExp, b: string | RegExp, str: string) => false | {
+    start: number;
+    end: number;
+    pre: string;
+    body: string;
+    post: string;
+} | undefined;
+export declare const range: (a: string, b: string, str: string) => undefined | [number, number];
+//# sourceMappingURL=index.d.ts.map