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/temp-dir/readme.md

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+# temp-dir [![Build Status](https://travis-ci.org/sindresorhus/temp-dir.svg?branch=master)](https://travis-ci.org/sindresorhus/temp-dir)
+
+> Get the real path of the system temp directory
+
+[The `os.tmpdir()` built-in doesn't return the real path.](https://github.com/nodejs/node/issues/11422) That can cause problems when the returned path is a symlink, which is the case on macOS. Use this module to get the resolved path.
+
+
+## Install
+
+```
+$ npm install temp-dir
+```
+
+
+## Usage
+
+```js
+const tempDirectory = require('temp-dir');
+
+console.log(tempDirectory);
+//=> '/private/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T'
+
+console.log(require('os').tmpdir());
+//=> '/var/folders/3x/jf5977fn79jbglr7rk0tq4d00000gn/T' // <= Symlink
+```
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)