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/safe-push-apply/CHANGELOG.md

@@ -0,0 +1,15 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## v1.0.0 - 2024-12-28
+
+### Commits
+
+- Initial implementation, tests, readme, types [`6e85f82`](https://github.com/ljharb/safe-push-apply/commit/6e85f82b116286503ff377e15708cd1584531c5f)
+- Initial commit [`93928d9`](https://github.com/ljharb/safe-push-apply/commit/93928d9a1304ccc25b799528a4bbca8615f7614e)
+- npm init [`5da39da`](https://github.com/ljharb/safe-push-apply/commit/5da39da33bb096e633d1e631a9374cfa0d7dc06b)
+- Only apps should have lockfiles [`83fc8b4`](https://github.com/ljharb/safe-push-apply/commit/83fc8b4be29d680a27225329cc1ef5505626effa)