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/regjsparser/README.md

@@ -0,0 +1,47 @@
+# RegJSParser
+
+Parsing the JavaScript's RegExp in JavaScript.
+
+## Installation
+
+```bash
+npm install regjsparser
+```
+
+## Usage
+
+```js
+var parse = require('regjsparser').parse;
+
+var parseTree = parse('^a'); // /^a/
+console.log(parseTree);
+
+// Toggle on/off additional features:
+var parseTree = parse('^a', '', {
+  // SEE: https://github.com/jviereck/regjsparser/pull/78
+  unicodePropertyEscape: true,
+
+  // SEE: https://github.com/jviereck/regjsparser/pull/83
+  namedGroups: true,
+
+  // SEE: https://github.com/jviereck/regjsparser/pull/89
+  lookbehind: true
+});
+console.log(parseTree);
+```
+
+## Testing
+
+To run the tests, run the following command:
+
+```bash
+npm test
+```
+
+To create a new reference file, execute…
+
+```bash
+node test/update-fixtures.js
+```
+
+…from the repo top directory.