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/semver/range.bnf

@@ -0,0 +1,16 @@
+range-set  ::= range ( logical-or range ) *
+logical-or ::= ( ' ' ) * '||' ( ' ' ) *
+range      ::= hyphen | simple ( ' ' simple ) * | ''
+hyphen     ::= partial ' - ' partial
+simple     ::= primitive | partial | tilde | caret
+primitive  ::= ( '<' | '>' | '>=' | '<=' | '=' ) partial
+partial    ::= xr ( '.' xr ( '.' xr qualifier ? )? )?
+xr         ::= 'x' | 'X' | '*' | nr
+nr         ::= '0' | [1-9] ( [0-9] ) *
+tilde      ::= '~' partial
+caret      ::= '^' partial
+qualifier  ::= ( '-' pre )? ( '+' build )?
+pre        ::= parts
+build      ::= parts
+parts      ::= part ( '.' part ) *
+part       ::= nr | [-0-9A-Za-z]+