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/fs-extra/lib/move-sync/move-sync.js

@@ -0,0 +1,47 @@
+'use strict'
+
+const fs = require('graceful-fs')
+const path = require('path')
+const copySync = require('../copy-sync').copySync
+const removeSync = require('../remove').removeSync
+const mkdirpSync = require('../mkdirs').mkdirpSync
+const stat = require('../util/stat')
+
+function moveSync (src, dest, opts) {
+  opts = opts || {}
+  const overwrite = opts.overwrite || opts.clobber || false
+
+  const { srcStat } = stat.checkPathsSync(src, dest, 'move')
+  stat.checkParentPathsSync(src, srcStat, dest, 'move')
+  mkdirpSync(path.dirname(dest))
+  return doRename(src, dest, overwrite)
+}
+
+function doRename (src, dest, overwrite) {
+  if (overwrite) {
+    removeSync(dest)
+    return rename(src, dest, overwrite)
+  }
+  if (fs.existsSync(dest)) throw new Error('dest already exists.')
+  return rename(src, dest, overwrite)
+}
+
+function rename (src, dest, overwrite) {
+  try {
+    fs.renameSync(src, dest)
+  } catch (err) {
+    if (err.code !== 'EXDEV') throw err
+    return moveAcrossDevice(src, dest, overwrite)
+  }
+}
+
+function moveAcrossDevice (src, dest, overwrite) {
+  const opts = {
+    overwrite,
+    errorOnExist: true
+  }
+  copySync(src, dest, opts)
+  return removeSync(src)
+}
+
+module.exports = moveSync