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/path-key/readme.md

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+# path-key [![Build Status](https://travis-ci.org/sindresorhus/path-key.svg?branch=master)](https://travis-ci.org/sindresorhus/path-key)
+
+> Get the [PATH](https://en.wikipedia.org/wiki/PATH_(variable)) environment variable key cross-platform
+
+It's usually `PATH`, but on Windows it can be any casing like `Path`...
+
+
+## Install
+
+```
+$ npm install path-key
+```
+
+
+## Usage
+
+```js
+const pathKey = require('path-key');
+
+const key = pathKey();
+//=> 'PATH'
+
+const PATH = process.env[key];
+//=> '/usr/local/bin:/usr/bin:/bin'
+```
+
+
+## API
+
+### pathKey(options?)
+
+#### options
+
+Type: `object`
+
+##### env
+
+Type: `object`<br>
+Default: [`process.env`](https://nodejs.org/api/process.html#process_process_env)
+
+Use a custom environment variables object.
+
+#### platform
+
+Type: `string`<br>
+Default: [`process.platform`](https://nodejs.org/api/process.html#process_process_platform)
+
+Get the PATH key for a specific platform.
+
+
+---
+
+<div align="center">
+	<b>
+		<a href="https://tidelift.com/subscription/pkg/npm-path-key?utm_source=npm-path-key&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>