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/regenerate-unicode-properties/Script/Tulu_Tigalari.js

@@ -0,0 +1,3 @@
+const set = require('regenerate')(0x1138B, 0x1138E, 0x113C2, 0x113C5);
+set.addRange(0x11380, 0x11389).addRange(0x11390, 0x113B5).addRange(0x113B7, 0x113C0).addRange(0x113C7, 0x113CA).addRange(0x113CC, 0x113D5).addRange(0x113D7, 0x113D8).addRange(0x113E1, 0x113E2);
+exports.characters = set;