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/fs-extra/lib/json/index.js

@@ -0,0 +1,16 @@
+'use strict'
+
+const u = require('universalify').fromPromise
+const jsonFile = require('./jsonfile')
+
+jsonFile.outputJson = u(require('./output-json'))
+jsonFile.outputJsonSync = require('./output-json-sync')
+// aliases
+jsonFile.outputJSON = jsonFile.outputJson
+jsonFile.outputJSONSync = jsonFile.outputJsonSync
+jsonFile.writeJSON = jsonFile.writeJson
+jsonFile.writeJSONSync = jsonFile.writeJsonSync
+jsonFile.readJSON = jsonFile.readJson
+jsonFile.readJSONSync = jsonFile.readJsonSync
+
+module.exports = jsonFile