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/vite-plugin-pwa/info.d.ts

@@ -0,0 +1,66 @@
+declare module 'virtual:pwa-info' {
+  export interface PwaInfo {
+    pwaInDevEnvironment: boolean
+    /**
+     * The web manifest will be always here.
+     */
+    webManifest: {
+      href: string
+      useCredentials: boolean
+      /**
+       * The link tag with or without `crossorigin`:
+       * - `<link rel="manifest" href="<webManifestUrl>" />`.
+       * - `<link rel="manifest" href="<webManifestUrl>" crossorigin="use-credentials" />`.
+       */
+      linkTag: string
+    }
+    /**
+     * The service worker data will be exposed only if required, that's, will **NOT** be exposed if:
+     * - not using `pwaPluginOptions.injectRegister` with `script`, `script-defer` or `inline` values
+     * - if using `pwaPluginOptions.injectRegister` with `auto` (default) and importing any of the virtual modules
+     */
+    registerSW?: {
+      /**
+       * When this flag is `true` the service worker must be registered via inline script otherwise registered via script with src attribute `registerSW.js`.
+       *
+       * @deprecated From `v0.17.2` this flag is deprecated, use `mode` instead.
+       */
+      inline: boolean
+      /**
+       * When this flag is `inline` the service worker must be registered via inline script otherwise registered via script with src attribute `registerSW.js`.
+       */
+      mode: 'inline' | 'script' | 'script-defer'
+      /**
+       * The path for the inline script: will contain the service worker url.
+       */
+      inlinePath: string
+      /**
+       * The path for the src script for `registerSW.js`.
+       */
+      registerPath: string
+      /**
+       * The scope for the service worker: only required for `inline: true`.
+       */
+      scope: string
+      /**
+       * The type for the service worker: only required for `inline: true`.
+       */
+      type: 'classic' | 'module'
+      /**
+       * The script tag if `shouldRegisterSW` returns `true`.
+       */
+      scriptTag?: string
+    }
+  }
+  /**
+   * Return the PWA information if available.
+   *
+   * This property will be `undefined` if:
+   * - SSR build
+   * - PWA is disabled: `pwaPluginOptions.disable = true`
+   * - running `Dev Server` and `pwaPluginOptions.devOptions.enabled = false` (default).
+   *
+   * @returns The PWA information.
+   */
+  export const pwaInfo: PwaInfo | undefined
+}