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-weakset/README.md

@@ -0,0 +1,50 @@
+# is-weakset <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]
+
+Is this value a JS WeakSet? This module works cross-realm/iframe, and despite ES6 @@toStringTag.
+
+## Example
+
+```js
+var isWeakSet = require('is-weakset');
+assert(!isWeakSet(function () {}));
+assert(!isWeakSet(null));
+assert(!isWeakSet(function* () { yield 42; return Infinity; });
+assert(!isWeakSet(Symbol('foo')));
+assert(!isWeakSet(1n));
+assert(!isWeakSet(Object(1n)));
+
+assert(!isWeakSet(new Set()));
+assert(!isWeakSet(new WeakMap()));
+assert(!isWeakSet(new Map()));
+
+assert(isWeakSet(new WeakSet()));
+
+class MyWeakSet extends WeakSet {}
+assert(isWeakSet(new MyWeakSet()));
+```
+
+## Tests
+Simply clone the repo, `npm install`, and run `npm test`
+
+[package-url]: https://npmjs.org/package/is-weakset
+[npm-version-svg]: https://versionbadg.es/inspect-js/is-weakset.svg
+[deps-svg]: https://david-dm.org/inspect-js/is-weakset.svg
+[deps-url]: https://david-dm.org/inspect-js/is-weakset
+[dev-deps-svg]: https://david-dm.org/inspect-js/is-weakset/dev-status.svg
+[dev-deps-url]: https://david-dm.org/inspect-js/is-weakset#info=devDependencies
+[npm-badge-png]: https://nodei.co/npm/is-weakset.png?downloads=true&stars=true
+[license-image]: https://img.shields.io/npm/l/is-weakset.svg
+[license-url]: LICENSE
+[downloads-image]: https://img.shields.io/npm/dm/is-weakset.svg
+[downloads-url]: https://npm-stat.com/charts.html?package=is-weakset
+[codecov-image]: https://codecov.io/gh/inspect-js/is-weakset/branch/main/graphs/badge.svg
+[codecov-url]: https://app.codecov.io/gh/inspect-js/is-weakset/
+[actions-image]: https://img.shields.io/endpoint?url=https://github-actions-badge-u3jn4tfpocch.runkit.sh/inspect-js/is-weakset
+[actions-url]: https://github.com/inspect-js/is-weakset/actions