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/tinyrainbow/README.md

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+# tinyrainbow
+
+Output your colorful messages in the terminal or browser console that support ANSI colors (Chrome engines).
+
+A small (`~ 6 kB` unpacked) fork of [picocolors](https://www.npmjs.com/package/picocolors) with support for `exports` field.
+
+Supports only ESM.
+
+## Installing
+
+```bash
+# with npm
+$ npm install -D tinyrainbow
+
+# with pnpm
+$ pnpm add -D tinyrainbow
+
+# with yarn
+$ yarn add -D tinyrainbow
+```
+
+## Usage
+
+```js
+import c from 'tinyrainbow'
+
+console.log(c.red(c.bold('Hello World!')))
+```