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/node-releases/README.md

@@ -0,0 +1,12 @@
+# Node.js releases data
+
+All data is located in `data` directory.
+
+`data/processed` contains `envs.json` with node.js releases data preprocessed to be used by [Browserslist](https://github.com/ai/browserslist) and other projects. Each version in this file contains only necessary info: version, release date, LTS flag/name, and security flag.
+
+`data/release-schedule` contains `release-schedule.json` with node.js releases date and end of life date.
+
+## Installation
+```bash
+npm install node-releases
+```