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/unicode-match-property-ecmascript/README.md

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+# unicode-match-property-ecmascript [![Build status](https://travis-ci.org/mathiasbynens/unicode-match-property-ecmascript.svg?branch=main)](https://travis-ci.org/mathiasbynens/unicode-match-property-ecmascript) [![unicode-match-property-ecmascript on npm](https://img.shields.io/npm/v/unicode-match-property-ecmascript)](https://www.npmjs.com/package/unicode-match-property-ecmascript)
+
+_unicode-match-property-ecmascript_ matches a given Unicode property or [property alias](https://github.com/mathiasbynens/unicode-property-aliases-ecmascript) to its canonical property name without applying [loose matching](https://github.com/mathiasbynens/unicode-loose-match) per the algorithm used for [RegExp Unicode property escapes in ECMAScript](https://github.com/tc39/proposal-regexp-unicode-property-escapes). Consider it a strict alternative to loose matching.
+
+## Installation
+
+To use _unicode-match-property-ecmascript_ programmatically, install it as a dependency via [npm](https://www.npmjs.com/):
+
+```bash
+$ npm install unicode-match-property-ecmascript
+```
+
+Then, `require` it:
+
+```js
+const matchProperty = require('unicode-match-property-ecmascript');
+```
+
+## API
+
+This module exports a single function named `matchProperty`.
+
+### `matchProperty(value)`
+
+This function takes a string `value` and attempts to match it to a canonical Unicode property name. If there’s a match, it returns the canonical property name. Otherwise, it throws an exception.
+
+```js
+// Find the canonical property name:
+matchProperty('sc')
+// → 'Script'
+
+matchProperty('Script')
+// → 'Script'
+
+matchProperty('script') // Note: incorrect casing.
+// → throws
+```
+
+## For maintainers
+
+### How to publish a new release
+
+1. On the `main` branch, bump the version number in `package.json`:
+
+    ```sh
+    npm version patch -m 'Release v%s'
+    ```
+
+    Instead of `patch`, use `minor` or `major` [as needed](https://semver.org/).
+
+    Note that this produces a Git commit + tag.
+
+1. Push the release commit and tag:
+
+    ```sh
+    git push && git push --tags
+    ```
+
+    Our CI then automatically publishes the new release to npm.
+
+## Author
+
+| [![twitter/mathias](https://gravatar.com/avatar/24e08a9ea84deb17ae121074d0f17125?s=70)](https://twitter.com/mathias "Follow @mathias on Twitter") |
+|---|
+| [Mathias Bynens](https://mathiasbynens.be/) |
+
+## License
+
+_unicode-match-property-ecmascript_ is available under the [MIT](https://mths.be/mit) license.