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/vitest/globals.d.ts

@@ -0,0 +1,19 @@
+declare global {
+  const suite: typeof import('vitest')['suite']
+  const test: typeof import('vitest')['test']
+  const describe: typeof import('vitest')['describe']
+  const it: typeof import('vitest')['it']
+  const expectTypeOf: typeof import('vitest')['expectTypeOf']
+  const assertType: typeof import('vitest')['assertType']
+  const expect: typeof import('vitest')['expect']
+  const assert: typeof import('vitest')['assert']
+  const vitest: typeof import('vitest')['vitest']
+  const vi: typeof import('vitest')['vitest']
+  const beforeAll: typeof import('vitest')['beforeAll']
+  const afterAll: typeof import('vitest')['afterAll']
+  const beforeEach: typeof import('vitest')['beforeEach']
+  const afterEach: typeof import('vitest')['afterEach']
+  const onTestFailed: typeof import('vitest')['onTestFailed']
+  const onTestFinished: typeof import('vitest')['onTestFinished']
+}
+export {}