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/json-schema-traverse/package.json

@@ -0,0 +1,43 @@
+{
+  "name": "json-schema-traverse",
+  "version": "1.0.0",
+  "description": "Traverse JSON Schema passing each schema object to callback",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "scripts": {
+    "eslint": "eslint index.js spec",
+    "test-spec": "mocha spec -R spec",
+    "test": "npm run eslint && nyc npm run test-spec"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/epoberezkin/json-schema-traverse.git"
+  },
+  "keywords": [
+    "JSON-Schema",
+    "traverse",
+    "iterate"
+  ],
+  "author": "Evgeny Poberezkin",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/epoberezkin/json-schema-traverse/issues"
+  },
+  "homepage": "https://github.com/epoberezkin/json-schema-traverse#readme",
+  "devDependencies": {
+    "eslint": "^7.3.1",
+    "mocha": "^8.0.1",
+    "nyc": "^15.0.0",
+    "pre-commit": "^1.2.2"
+  },
+  "nyc": {
+    "exclude": [
+      "**/spec/**",
+      "node_modules"
+    ],
+    "reporter": [
+      "lcov",
+      "text-summary"
+    ]
+  }
+}