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/json5/lib/parse.d.ts

@@ -0,0 +1,15 @@
+/**
+ * Parses a JSON5 string, constructing the JavaScript value or object described
+ * by the string.
+ * @template T The type of the return value.
+ * @param text The string to parse as JSON5.
+ * @param reviver A function that prescribes how the value originally produced
+ * by parsing is transformed before being returned.
+ * @returns The JavaScript value converted from the JSON5 string.
+ */
+declare function parse<T = any>(
+    text: string,
+    reviver?: ((this: any, key: string, value: any) => any) | null,
+): T
+
+export = parse