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/at-least-node/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "at-least-node",
+  "version": "1.0.0",
+  "description": "Lightweight Node.js version sniffing/comparison",
+  "keywords": [
+    "semver",
+    "feature"
+  ],
+  "homepage": "https://github.com/RyanZim/at-least-node#readme",
+  "bugs": {
+    "url": "https://github.com/RyanZim/at-least-node/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/RyanZim/at-least-node.git"
+  },
+  "license": "ISC",
+  "author": "Ryan Zimmerman <opensrc@ryanzim.com>",
+  "main": "index.js",
+  "files": [],
+  "scripts": {
+    "test": "ava"
+  },
+  "devDependencies": {
+    "ava": "^3.1.0",
+    "rewire": "^4.0.1",
+    "semver": "^7.1.2"
+  },
+  "engines": {
+    "node": ">= 4.0.0"
+  }
+}