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/workbox-build/build/templates/sw-template.d.ts

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+export declare const swTemplate = "/**\n * Welcome to your Workbox-powered service worker!\n *\n * You'll need to register this file in your web app.\n * See https://goo.gl/nhQhGp\n *\n * The rest of the code is auto-generated. Please don't update this file\n * directly; instead, make changes to your Workbox build configuration\n * and re-run your build process.\n * See https://goo.gl/2aRDsh\n */\n\n<% if (importScripts) { %>\nimportScripts(\n  <%= importScripts.map(JSON.stringify).join(',\\n  ') %>\n);\n<% } %>\n\n<% if (navigationPreload) { %><%= use('workbox-navigation-preload', 'enable') %>();<% } %>\n\n<% if (cacheId) { %><%= use('workbox-core', 'setCacheNameDetails') %>({prefix: <%= JSON.stringify(cacheId) %>});<% } %>\n\n<% if (skipWaiting) { %>\nself.skipWaiting();\n<% } else { %>\nself.addEventListener('message', (event) => {\n  if (event.data && event.data.type === 'SKIP_WAITING') {\n    self.skipWaiting();\n  }\n});\n<% } %>\n<% if (clientsClaim) { %><%= use('workbox-core', 'clientsClaim') %>();<% } %>\n\n<% if (Array.isArray(manifestEntries) && manifestEntries.length > 0) {%>\n/**\n * The precacheAndRoute() method efficiently caches and responds to\n * requests for URLs in the manifest.\n * See https://goo.gl/S9QRab\n */\n<%= use('workbox-precaching', 'precacheAndRoute') %>(<%= JSON.stringify(manifestEntries, null, 2) %>, <%= precacheOptionsString %>);\n<% if (cleanupOutdatedCaches) { %><%= use('workbox-precaching', 'cleanupOutdatedCaches') %>();<% } %>\n<% if (navigateFallback) { %><%= use('workbox-routing', 'registerRoute') %>(new <%= use('workbox-routing', 'NavigationRoute') %>(<%= use('workbox-precaching', 'createHandlerBoundToURL') %>(<%= JSON.stringify(navigateFallback) %>)<% if (navigateFallbackAllowlist || navigateFallbackDenylist) { %>, {\n  <% if (navigateFallbackAllowlist) { %>allowlist: [<%= navigateFallbackAllowlist %>],<% } %>\n  <% if (navigateFallbackDenylist) { %>denylist: [<%= navigateFallbackDenylist %>],<% } %>\n}<% } %>));<% } %>\n<% } %>\n\n<% if (runtimeCaching) { runtimeCaching.forEach(runtimeCachingString => {%><%= runtimeCachingString %><% });} %>\n\n<% if (offlineAnalyticsConfigString) { %><%= use('workbox-google-analytics', 'initialize') %>(<%= offlineAnalyticsConfigString %>);<% } %>\n\n<% if (disableDevLogs) { %>self.__WB_DISABLE_DEV_LOGS = true;<% } %>";