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-stream/readme.md

@@ -0,0 +1,60 @@
+# is-stream
+
+> Check if something is a [Node.js stream](https://nodejs.org/api/stream.html)
+
+## Install
+
+```
+$ npm install is-stream
+```
+
+## Usage
+
+```js
+const fs = require('fs');
+const isStream = require('is-stream');
+
+isStream(fs.createReadStream('unicorn.png'));
+//=> true
+
+isStream({});
+//=> false
+```
+
+## API
+
+### isStream(stream)
+
+Returns a `boolean` for whether it's a [`Stream`](https://nodejs.org/api/stream.html#stream_stream).
+
+#### isStream.writable(stream)
+
+Returns a `boolean` for whether it's a [`stream.Writable`](https://nodejs.org/api/stream.html#stream_class_stream_writable).
+
+#### isStream.readable(stream)
+
+Returns a `boolean` for whether it's a [`stream.Readable`](https://nodejs.org/api/stream.html#stream_class_stream_readable).
+
+#### isStream.duplex(stream)
+
+Returns a `boolean` for whether it's a [`stream.Duplex`](https://nodejs.org/api/stream.html#stream_class_stream_duplex).
+
+#### isStream.transform(stream)
+
+Returns a `boolean` for whether it's a [`stream.Transform`](https://nodejs.org/api/stream.html#stream_class_stream_transform).
+
+## Related
+
+- [is-file-stream](https://github.com/jamestalmage/is-file-stream) - Detect if a stream is a file stream
+
+---
+
+<div align="center">
+	<b>
+		<a href="https://tidelift.com/subscription/pkg/npm-is-stream?utm_source=npm-is-stream&utm_medium=referral&utm_campaign=readme">Get professional support for this package with a Tidelift subscription</a>
+	</b>
+	<br>
+	<sub>
+		Tidelift helps make open source sustainable for maintainers while giving companies<br>assurances about security, maintenance, and licensing for their dependencies.
+	</sub>
+</div>