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/universalify/README.md

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+# universalify
+
+![GitHub Workflow Status (branch)](https://img.shields.io/github/actions/workflow/status/RyanZim/universalify/ci.yml?branch=master)
+![Coveralls github branch](https://img.shields.io/coveralls/github/RyanZim/universalify/master.svg)
+![npm](https://img.shields.io/npm/dm/universalify.svg)
+![npm](https://img.shields.io/npm/l/universalify.svg)
+
+Make a callback- or promise-based function support both promises and callbacks.
+
+Uses the native promise implementation.
+
+## Installation
+
+```bash
+npm install universalify
+```
+
+## API
+
+### `universalify.fromCallback(fn)`
+
+Takes a callback-based function to universalify, and returns the universalified  function.
+
+Function must take a callback as the last parameter that will be called with the signature `(error, result)`. `universalify` does not support calling the callback with three or more arguments, and does not ensure that the callback is only called once.
+
+```js
+function callbackFn (n, cb) {
+  setTimeout(() => cb(null, n), 15)
+}
+
+const fn = universalify.fromCallback(callbackFn)
+
+// Works with Promises:
+fn('Hello World!')
+.then(result => console.log(result)) // -> Hello World!
+.catch(error => console.error(error))
+
+// Works with Callbacks:
+fn('Hi!', (error, result) => {
+  if (error) return console.error(error)
+  console.log(result)
+  // -> Hi!
+})
+```
+
+### `universalify.fromPromise(fn)`
+
+Takes a promise-based function to universalify, and returns the universalified  function.
+
+Function must return a valid JS promise. `universalify` does not ensure that a valid promise is returned.
+
+```js
+function promiseFn (n) {
+  return new Promise(resolve => {
+    setTimeout(() => resolve(n), 15)
+  })
+}
+
+const fn = universalify.fromPromise(promiseFn)
+
+// Works with Promises:
+fn('Hello World!')
+.then(result => console.log(result)) // -> Hello World!
+.catch(error => console.error(error))
+
+// Works with Callbacks:
+fn('Hi!', (error, result) => {
+  if (error) return console.error(error)
+  console.log(result)
+  // -> Hi!
+})
+```
+
+## License
+
+MIT