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/postcss/lib/previous-map.d.ts

@@ -0,0 +1,81 @@
+import { SourceMapConsumer } from 'source-map-js'
+
+import { ProcessOptions } from './postcss.js'
+
+declare namespace PreviousMap {
+   
+  export { PreviousMap_ as default }
+}
+
+/**
+ * Source map information from input CSS.
+ * For example, source map after Sass compiler.
+ *
+ * This class will automatically find source map in input CSS or in file system
+ * near input file (according `from` option).
+ *
+ * ```js
+ * const root = parse(css, { from: 'a.sass.css' })
+ * root.input.map //=> PreviousMap
+ * ```
+ */
+declare class PreviousMap_ {
+  /**
+   * `sourceMappingURL` content.
+   */
+  annotation?: string
+
+  /**
+   * The CSS source identifier. Contains `Input#file` if the user
+   * set the `from` option, or `Input#id` if they did not.
+   */
+  file?: string
+
+  /**
+   * Was source map inlined by data-uri to input CSS.
+   */
+  inline: boolean
+
+  /**
+   * Path to source map file.
+   */
+  mapFile?: string
+
+  /**
+   * The directory with source map file, if source map is in separated file.
+   */
+  root?: string
+
+  /**
+   * Source map file content.
+   */
+  text?: string
+
+  /**
+   * @param css  Input CSS source.
+   * @param opts Process options.
+   */
+  constructor(css: string, opts?: ProcessOptions)
+
+  /**
+   * Create a instance of `SourceMapGenerator` class
+   * from the `source-map` library to work with source map information.
+   *
+   * It is lazy method, so it will create object only on first call
+   * and then it will use cache.
+   *
+   * @return Object with source map information.
+   */
+  consumer(): SourceMapConsumer
+
+  /**
+   * Does source map contains `sourcesContent` with input source text.
+   *
+   * @return Is `sourcesContent` present.
+   */
+  withContent(): boolean
+}
+
+declare class PreviousMap extends PreviousMap_ {}
+
+export = PreviousMap