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/async-function/README.md

@@ -0,0 +1,51 @@
+# async-function <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
+
+[![github actions][actions-image]][actions-url]
+[![coverage][codecov-image]][codecov-url]
+[![License][license-image]][license-url]
+[![Downloads][downloads-image]][downloads-url]
+
+[![npm badge][npm-badge-png]][package-url]
+
+A function that returns the normally hidden `AsyncFunction` constructor, when available.
+
+## Getting started
+
+```sh
+npm install --save async-function
+```
+
+## Usage/Examples
+
+```js
+const assert = require('assert');
+const AsyncFunction = require('async-function')();
+
+const fn = new AsyncFunction('return 1');
+
+assert.equal(fn.toString(), 'async function anonymous(\n) {\nreturn 1\n}');
+
+fn().then(x => {
+    assert.equal(x, 1);
+});
+```
+
+## Tests
+
+Clone the repo, `npm install`, and run `npm test`
+
+[package-url]: https://npmjs.org/package/async-function
+[npm-version-svg]: https://versionbadg.es/ljharb/async-function.svg
+[deps-svg]: https://david-dm.org/ljharb/async-function.svg
+[deps-url]: https://david-dm.org/ljharb/async-function
+[dev-deps-svg]: https://david-dm.org/ljharb/async-function/dev-status.svg
+[dev-deps-url]: https://david-dm.org/ljharb/async-function#info=devDependencies
+[npm-badge-png]: https://nodei.co/npm/async-function.png?downloads=true&stars=true
+[license-image]: https://img.shields.io/npm/l/async-function.svg
+[license-url]: LICENSE
+[downloads-image]: https://img.shields.io/npm/dm/async-function.svg
+[downloads-url]: https://npm-stat.com/charts.html?package=async-function
+[codecov-image]: https://codecov.io/gh/ljharb/async-function/branch/main/graphs/badge.svg
+[codecov-url]: https://app.codecov.io/gh/ljharb/async-function/
+[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/ljharb/async-function
+[actions-url]: https://github.com/ljharb/async-function/actions