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/get-symbol-description/getInferredName.js

@@ -0,0 +1,13 @@
+'use strict';
+
+/** @type {NonNullable<import('./getInferredName')> | undefined} */
+var getInferredName;
+try {
+	// eslint-disable-next-line no-new-func, no-extra-parens
+	getInferredName = /** @type {NonNullable<import('./getInferredName')>} */ (Function('s', 'return { [s]() {} }[s].name;'));
+} catch (e) {}
+
+var inferred = function () {};
+
+/** @type {import('./getInferredName')} */
+module.exports = getInferredName && inferred.name === 'inferred' ? getInferredName : null;