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/is-obj/readme.md

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+# is-obj [![Build Status](https://travis-ci.org/sindresorhus/is-obj.svg?branch=master)](https://travis-ci.org/sindresorhus/is-obj)
+
+> Check if a value is an object
+
+Keep in mind that array, function, regexp, etc, are objects in JavaScript.<br>
+See [`is-plain-obj`](https://github.com/sindresorhus/is-plain-obj) if you want to check for plain objects.
+
+
+## Install
+
+```
+$ npm install --save is-obj
+```
+
+
+## Usage
+
+```js
+const isObj = require('is-obj');
+
+isObj({foo: 'bar'});
+//=> true
+
+isObj([1, 2, 3]);
+//=> true
+
+isObj('foo');
+//=> false
+```
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)