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-uri/.github/workflows/package-manager-ci.yml

@@ -0,0 +1,24 @@
+name: package-manager-ci
+
+on:
+  push:
+    branches:
+     - main
+     - next
+     - 'v*'
+    paths-ignore:
+      - 'docs/**'
+      - '*.md'
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - '*.md'
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    permissions:
+      contents: read
+    uses: fastify/workflows/.github/workflows/plugins-ci-package-manager.yml@v5