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/@rollup/plugin-terser/README.md

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+[npm]: https://img.shields.io/npm/v/@rollup/plugin-terser
+[npm-url]: https://www.npmjs.com/package/@rollup/plugin-terser
+[size]: https://packagephobia.now.sh/badge?p=@rollup/plugin-terser
+[size-url]: https://packagephobia.now.sh/result?p=@rollup/plugin-terser
+
+[![npm][npm]][npm-url]
+[![size][size]][size-url]
+[![libera manifesto](https://img.shields.io/badge/libera-manifesto-lightgrey.svg)](https://liberamanifesto.com)
+
+# @rollup/plugin-terser
+
+🍣 A Rollup plugin to generate a minified bundle with terser.
+
+## Requirements
+
+This plugin requires an [LTS](https://github.com/nodejs/Release) Node version (v14.0.0+) and Rollup v2.0+.
+
+## Install
+
+Using npm:
+
+```console
+npm install @rollup/plugin-terser --save-dev
+```
+
+## Usage
+
+Create a `rollup.config.js` [configuration file](https://www.rollupjs.org/guide/en/#configuration-files) and import the plugin:
+
+```typescript
+import terser from '@rollup/plugin-terser';
+
+export default {
+  input: 'src/index.js',
+  output: {
+    dir: 'output',
+    format: 'cjs'
+  },
+  plugins: [terser()]
+};
+```
+
+Then call `rollup` either via the [CLI](https://www.rollupjs.org/guide/en/#command-line-reference) or the [API](https://www.rollupjs.org/guide/en/#javascript-api).
+
+## Options
+
+The plugin accepts a terser [Options](https://github.com/terser/terser#minify-options) object as input parameter,
+to modify the default behaviour.
+
+In addition to the `terser` options, it is also possible to provide the following options:
+
+### `maxWorkers`
+
+Type: `Number`<br>
+Default: `undefined`
+
+Instructs the plugin to use a specific amount of cpu threads.
+
+```typescript
+import terser from '@rollup/plugin-terser';
+
+export default {
+  input: 'src/index.js',
+  output: {
+    dir: 'output',
+    format: 'cjs'
+  },
+  plugins: [
+    terser({
+      maxWorkers: 4
+    })
+  ]
+};
+```
+
+## Meta
+
+[CONTRIBUTING](/.github/CONTRIBUTING.md)
+
+[LICENSE (MIT)](/LICENSE)