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/crypto-random-string/readme.md

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+# crypto-random-string [![Build Status](https://travis-ci.org/sindresorhus/crypto-random-string.svg?branch=master)](https://travis-ci.org/sindresorhus/crypto-random-string)
+
+> Generate a [cryptographically strong](https://en.m.wikipedia.org/wiki/Strong_cryptography) random string
+
+Can be useful for creating an identifier, slug, salt, fixture, etc.
+
+
+## Install
+
+```
+$ npm install crypto-random-string
+```
+
+
+## Usage
+
+```js
+const cryptoRandomString = require('crypto-random-string');
+
+cryptoRandomString(10);
+//=> '2cf05d94db'
+```
+
+
+## API
+
+### cryptoRandomString(length)
+
+Returns a [`hex`](https://en.wikipedia.org/wiki/Hexadecimal) string.
+
+#### length
+
+Type: `number`
+
+Length of the returned string.
+
+
+## Related
+
+- [random-int](https://github.com/sindresorhus/random-int) - Generate a random integer
+- [random-float](https://github.com/sindresorhus/random-float) - Generate a random float
+- [random-item](https://github.com/sindresorhus/random-item) - Get a random item from an array
+- [random-boolean](https://github.com/arthurvr/random-boolean) - Get a random boolean
+- [random-obj-key](https://github.com/sindresorhus/random-obj-key) - Get a random key from an object
+- [random-obj-prop](https://github.com/sindresorhus/random-obj-prop) - Get a random property from an object
+- [unique-random](https://github.com/sindresorhus/unique-random) - Generate random numbers that are consecutively unique
+
+
+## License
+
+MIT © [Sindre Sorhus](https://sindresorhus.com)