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/jsonfile/package.json

@@ -0,0 +1,40 @@
+{
+  "name": "jsonfile",
+  "version": "6.2.0",
+  "description": "Easily read/write JSON files.",
+  "repository": {
+    "type": "git",
+    "url": "git@github.com:jprichardson/node-jsonfile.git"
+  },
+  "keywords": [
+    "read",
+    "write",
+    "file",
+    "json",
+    "fs",
+    "fs-extra"
+  ],
+  "author": "JP Richardson <jprichardson@gmail.com>",
+  "license": "MIT",
+  "dependencies": {
+    "universalify": "^2.0.0"
+  },
+  "optionalDependencies": {
+    "graceful-fs": "^4.1.6"
+  },
+  "devDependencies": {
+    "mocha": "^8.2.0",
+    "rimraf": "^2.4.0",
+    "standard": "^16.0.1"
+  },
+  "main": "index.js",
+  "files": [
+    "index.js",
+    "utils.js"
+  ],
+  "scripts": {
+    "lint": "standard",
+    "test": "npm run lint && npm run unit",
+    "unit": "mocha"
+  }
+}