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/caniuse-lite/dist/unpacker/agents.js

@@ -0,0 +1,47 @@
+'use strict'
+
+const browsers = require('./browsers').browsers
+const versions = require('./browserVersions').browserVersions
+const agentsData = require('../../data/agents')
+
+function unpackBrowserVersions(versionsData) {
+  return Object.keys(versionsData).reduce((usage, version) => {
+    usage[versions[version]] = versionsData[version]
+    return usage
+  }, {})
+}
+
+module.exports.agents = Object.keys(agentsData).reduce((map, key) => {
+  let versionsData = agentsData[key]
+  map[browsers[key]] = Object.keys(versionsData).reduce((data, entry) => {
+    if (entry === 'A') {
+      data.usage_global = unpackBrowserVersions(versionsData[entry])
+    } else if (entry === 'C') {
+      data.versions = versionsData[entry].reduce((list, version) => {
+        if (version === '') {
+          list.push(null)
+        } else {
+          list.push(versions[version])
+        }
+        return list
+      }, [])
+    } else if (entry === 'D') {
+      data.prefix_exceptions = unpackBrowserVersions(versionsData[entry])
+    } else if (entry === 'E') {
+      data.browser = versionsData[entry]
+    } else if (entry === 'F') {
+      data.release_date = Object.keys(versionsData[entry]).reduce(
+        (map2, key2) => {
+          map2[versions[key2]] = versionsData[entry][key2]
+          return map2
+        },
+        {}
+      )
+    } else {
+      // entry is B
+      data.prefix = versionsData[entry]
+    }
+    return data
+  }, {})
+  return map
+}, {})