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/utils/createCacheKey.js

@@ -0,0 +1,56 @@
+/*
+  Copyright 2018 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 { WorkboxError } from 'workbox-core/_private/WorkboxError.js';
+import '../_version.js';
+// Name of the search parameter used to store revision info.
+const REVISION_SEARCH_PARAM = '__WB_REVISION__';
+/**
+ * Converts a manifest entry into a versioned URL suitable for precaching.
+ *
+ * @param {Object|string} entry
+ * @return {string} A URL with versioning info.
+ *
+ * @private
+ * @memberof workbox-precaching
+ */
+export function createCacheKey(entry) {
+    if (!entry) {
+        throw new WorkboxError('add-to-cache-list-unexpected-type', { entry });
+    }
+    // If a precache manifest entry is a string, it's assumed to be a versioned
+    // URL, like '/app.abcd1234.js'. Return as-is.
+    if (typeof entry === 'string') {
+        const urlObject = new URL(entry, location.href);
+        return {
+            cacheKey: urlObject.href,
+            url: urlObject.href,
+        };
+    }
+    const { revision, url } = entry;
+    if (!url) {
+        throw new WorkboxError('add-to-cache-list-unexpected-type', { entry });
+    }
+    // If there's just a URL and no revision, then it's also assumed to be a
+    // versioned URL.
+    if (!revision) {
+        const urlObject = new URL(url, location.href);
+        return {
+            cacheKey: urlObject.href,
+            url: urlObject.href,
+        };
+    }
+    // Otherwise, construct a properly versioned URL using the custom Workbox
+    // search parameter along with the revision info.
+    const cacheKeyURL = new URL(url, location.href);
+    const originalURL = new URL(url, location.href);
+    cacheKeyURL.searchParams.set(REVISION_SEARCH_PARAM, revision);
+    return {
+        cacheKey: cacheKeyURL.href,
+        url: originalURL.href,
+    };
+}