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/webidl-conversions/package.json

@@ -0,0 +1,27 @@
+{
+  "name": "webidl-conversions",
+  "version": "4.0.2",
+  "description": "Implements the WebIDL algorithms for converting to and from JavaScript values",
+  "main": "lib/index.js",
+  "scripts": {
+    "lint": "eslint .",
+    "test": "mocha test/*.js",
+    "coverage": "nyc mocha test/*.js"
+  },
+  "repository": "jsdom/webidl-conversions",
+  "keywords": [
+    "webidl",
+    "web",
+    "types"
+  ],
+  "files": [
+    "lib/"
+  ],
+  "author": "Domenic Denicola <d@domenic.me> (https://domenic.me/)",
+  "license": "BSD-2-Clause",
+  "devDependencies": {
+    "eslint": "^3.15.0",
+    "mocha": "^1.21.4",
+    "nyc": "^10.1.2"
+  }
+}