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/workbox-core/index.d.ts

@@ -0,0 +1,17 @@
+import { registerQuotaErrorCallback } from './registerQuotaErrorCallback.js';
+import * as _private from './_private.js';
+import { cacheNames } from './cacheNames.js';
+import { copyResponse } from './copyResponse.js';
+import { clientsClaim } from './clientsClaim.js';
+import { setCacheNameDetails } from './setCacheNameDetails.js';
+import { skipWaiting } from './skipWaiting.js';
+import './_version.js';
+/**
+ * All of the Workbox service worker libraries use workbox-core for shared
+ * code as well as setting default values that need to be shared (like cache
+ * names).
+ *
+ * @module workbox-core
+ */
+export { _private, cacheNames, clientsClaim, copyResponse, registerQuotaErrorCallback, setCacheNameDetails, skipWaiting, };
+export * from './types.js';