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-precaching/PrecacheRoute.js

@@ -0,0 +1,57 @@
+/*
+  Copyright 2020 Google LLC
+
+  Use of this source code is governed by an MIT-style
+  license that can be found in the LICENSE file or at
+  https://opensource.org/licenses/MIT.
+*/
+import { logger } from 'workbox-core/_private/logger.js';
+import { getFriendlyURL } from 'workbox-core/_private/getFriendlyURL.js';
+import { Route } from 'workbox-routing/Route.js';
+import { generateURLVariations } from './utils/generateURLVariations.js';
+import './_version.js';
+/**
+ * A subclass of {@link workbox-routing.Route} that takes a
+ * {@link workbox-precaching.PrecacheController}
+ * instance and uses it to match incoming requests and handle fetching
+ * responses from the precache.
+ *
+ * @memberof workbox-precaching
+ * @extends workbox-routing.Route
+ */
+class PrecacheRoute extends Route {
+    /**
+     * @param {PrecacheController} precacheController A `PrecacheController`
+     * instance used to both match requests and respond to fetch events.
+     * @param {Object} [options] Options to control how requests are matched
+     * against the list of precached URLs.
+     * @param {string} [options.directoryIndex=index.html] The `directoryIndex` will
+     * check cache entries for a URLs ending with '/' to see if there is a hit when
+     * appending the `directoryIndex` value.
+     * @param {Array<RegExp>} [options.ignoreURLParametersMatching=[/^utm_/, /^fbclid$/]] An
+     * array of regex's to remove search params when looking for a cache match.
+     * @param {boolean} [options.cleanURLs=true] The `cleanURLs` option will
+     * check the cache for the URL with a `.html` added to the end of the end.
+     * @param {workbox-precaching~urlManipulation} [options.urlManipulation]
+     * This is a function that should take a URL and return an array of
+     * alternative URLs that should be checked for precache matches.
+     */
+    constructor(precacheController, options) {
+        const match = ({ request, }) => {
+            const urlsToCacheKeys = precacheController.getURLsToCacheKeys();
+            for (const possibleURL of generateURLVariations(request.url, options)) {
+                const cacheKey = urlsToCacheKeys.get(possibleURL);
+                if (cacheKey) {
+                    const integrity = precacheController.getIntegrityForCacheKey(cacheKey);
+                    return { cacheKey, integrity };
+                }
+            }
+            if (process.env.NODE_ENV !== 'production') {
+                logger.debug(`Precaching did not find a match for ` + getFriendlyURL(request.url));
+            }
+            return;
+        };
+        super(match, precacheController.strategy);
+    }
+}
+export { PrecacheRoute };