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/loupe/lib/date.js

@@ -0,0 +1,11 @@
+import { truncate } from './helpers.js';
+export default function inspectDate(dateObject, options) {
+    const stringRepresentation = dateObject.toJSON();
+    if (stringRepresentation === null) {
+        return 'Invalid Date';
+    }
+    const split = stringRepresentation.split('T');
+    const date = split[0];
+    // If we need to - truncate the time portion, but never the date
+    return options.stylize(`${date}T${truncate(split[1], options.truncate - date.length - 1)}`, 'date');
+}