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/set-proto/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 - 2024-12-30
+
+### Commits
+
+- Initial implementation, tests, readme, types [`7036fc9`](https://github.com/ljharb/set-proto/commit/7036fc9128568b1ff0b75d1955f7f364a4394079)
+- Initial commit [`dd9bedd`](https://github.com/ljharb/set-proto/commit/dd9bedd41db6ff3efa00c84fcac8ae34558bf6ee)
+- npm init [`63915de`](https://github.com/ljharb/set-proto/commit/63915dee39422698275fabe9876eb141e04390dd)
+- Only apps should have lockfiles [`deffdae`](https://github.com/ljharb/set-proto/commit/deffdae5b989a9305247a4db314222ecc0a99280)