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/ms/package.json

@@ -0,0 +1,38 @@
+{
+  "name": "ms",
+  "version": "2.1.3",
+  "description": "Tiny millisecond conversion utility",
+  "repository": "vercel/ms",
+  "main": "./index",
+  "files": [
+    "index.js"
+  ],
+  "scripts": {
+    "precommit": "lint-staged",
+    "lint": "eslint lib/* bin/*",
+    "test": "mocha tests.js"
+  },
+  "eslintConfig": {
+    "extends": "eslint:recommended",
+    "env": {
+      "node": true,
+      "es6": true
+    }
+  },
+  "lint-staged": {
+    "*.js": [
+      "npm run lint",
+      "prettier --single-quote --write",
+      "git add"
+    ]
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "eslint": "4.18.2",
+    "expect.js": "0.3.1",
+    "husky": "0.14.3",
+    "lint-staged": "5.0.0",
+    "mocha": "4.0.1",
+    "prettier": "2.0.5"
+  }
+}