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/vite-node/dist/source-map.d.ts

@@ -0,0 +1,14 @@
+import { TransformResult } from 'vite';
+import { E as EncodedSourceMap } from './trace-mapping.d-DLVdEqOp.js';
+
+interface InstallSourceMapSupportOptions {
+    getSourceMap: (source: string) => EncodedSourceMap | null | undefined;
+}
+declare function withInlineSourcemap(result: TransformResult, options: {
+    root: string;
+    filepath: string;
+}): TransformResult;
+declare function extractSourceMap(code: string): EncodedSourceMap | null;
+declare function installSourcemapsSupport(options: InstallSourceMapSupportOptions): void;
+
+export { extractSourceMap, installSourcemapsSupport, withInlineSourcemap };