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-strategies/NetworkOnly.d.ts

@@ -0,0 +1,43 @@
+import { Strategy, StrategyOptions } from './Strategy.js';
+import { StrategyHandler } from './StrategyHandler.js';
+import './_version.js';
+interface NetworkOnlyOptions extends Omit<StrategyOptions, 'cacheName' | 'matchOptions'> {
+    networkTimeoutSeconds?: number;
+}
+/**
+ * An implementation of a
+ * [network-only](https://developer.chrome.com/docs/workbox/caching-strategies-overview/#network-only)
+ * request strategy.
+ *
+ * This class is useful if you want to take advantage of any
+ * [Workbox plugins](https://developer.chrome.com/docs/workbox/using-plugins/).
+ *
+ * If the network request fails, this will throw a `WorkboxError` exception.
+ *
+ * @extends workbox-strategies.Strategy
+ * @memberof workbox-strategies
+ */
+declare class NetworkOnly extends Strategy {
+    private readonly _networkTimeoutSeconds;
+    /**
+     * @param {Object} [options]
+     * @param {Array<Object>} [options.plugins] [Plugins]{@link https://developers.google.com/web/tools/workbox/guides/using-plugins}
+     * to use in conjunction with this caching strategy.
+     * @param {Object} [options.fetchOptions] Values passed along to the
+     * [`init`](https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters)
+     * of [non-navigation](https://github.com/GoogleChrome/workbox/issues/1796)
+     * `fetch()` requests made by this strategy.
+     * @param {number} [options.networkTimeoutSeconds] If set, any network requests
+     * that fail to respond within the timeout will result in a network error.
+     */
+    constructor(options?: NetworkOnlyOptions);
+    /**
+     * @private
+     * @param {Request|string} request A request to run this strategy for.
+     * @param {workbox-strategies.StrategyHandler} handler The event that
+     *     triggered the request.
+     * @return {Promise<Response>}
+     */
+    _handle(request: Request, handler: StrategyHandler): Promise<Response>;
+}
+export { NetworkOnly, NetworkOnlyOptions };