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/snapshot/dist/environment.d.ts

@@ -0,0 +1,16 @@
+import { S as SnapshotEnvironment, a as SnapshotEnvironmentOptions } from './environment-Ddx0EDtY.js';
+
+declare class NodeSnapshotEnvironment implements SnapshotEnvironment {
+    private options;
+    constructor(options?: SnapshotEnvironmentOptions);
+    getVersion(): string;
+    getHeader(): string;
+    resolveRawPath(testPath: string, rawPath: string): Promise<string>;
+    resolvePath(filepath: string): Promise<string>;
+    prepareDirectory(dirPath: string): Promise<void>;
+    saveSnapshotFile(filepath: string, snapshot: string): Promise<void>;
+    readSnapshotFile(filepath: string): Promise<string | null>;
+    removeSnapshotFile(filepath: string): Promise<void>;
+}
+
+export { NodeSnapshotEnvironment, SnapshotEnvironment };