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/fast-json-stable-stringify/package.json

@@ -0,0 +1,52 @@
+{
+  "name": "fast-json-stable-stringify",
+  "version": "2.1.0",
+  "description": "deterministic `JSON.stringify()` - a faster version of substack's json-stable-strigify without jsonify",
+  "main": "index.js",
+  "types": "index.d.ts",
+  "dependencies": {},
+  "devDependencies": {
+    "benchmark": "^2.1.4",
+    "coveralls": "^3.0.0",
+    "eslint": "^6.7.0",
+    "fast-stable-stringify": "latest",
+    "faster-stable-stringify": "latest",
+    "json-stable-stringify": "latest",
+    "nyc": "^14.1.0",
+    "pre-commit": "^1.2.2",
+    "tape": "^4.11.0"
+  },
+  "scripts": {
+    "eslint": "eslint index.js test",
+    "test-spec": "tape test/*.js",
+    "test": "npm run eslint && nyc npm run test-spec"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git://github.com/epoberezkin/fast-json-stable-stringify.git"
+  },
+  "homepage": "https://github.com/epoberezkin/fast-json-stable-stringify",
+  "keywords": [
+    "json",
+    "stringify",
+    "deterministic",
+    "hash",
+    "stable"
+  ],
+  "author": {
+    "name": "James Halliday",
+    "email": "mail@substack.net",
+    "url": "http://substack.net"
+  },
+  "license": "MIT",
+  "nyc": {
+    "exclude": [
+      "test",
+      "node_modules"
+    ],
+    "reporter": [
+      "lcov",
+      "text-summary"
+    ]
+  }
+}