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-node/dist/trace-mapping.d-DLVdEqOp.d.ts

@@ -0,0 +1,57 @@
+type GeneratedColumn = number;
+type SourcesIndex = number;
+type SourceLine = number;
+type SourceColumn = number;
+type NamesIndex = number;
+type SourceMapSegment = [GeneratedColumn] | [GeneratedColumn, SourcesIndex, SourceLine, SourceColumn] | [GeneratedColumn, SourcesIndex, SourceLine, SourceColumn, NamesIndex];
+
+interface SourceMapV3 {
+    file?: string | null;
+    names: string[];
+    sourceRoot?: string;
+    sources: (string | null)[];
+    sourcesContent?: (string | null)[];
+    version: 3;
+    ignoreList?: number[];
+}
+interface EncodedSourceMap extends SourceMapV3 {
+    mappings: string;
+}
+interface DecodedSourceMap extends SourceMapV3 {
+    mappings: SourceMapSegment[][];
+}
+type XInput = {
+    x_google_ignoreList?: SourceMapV3['ignoreList'];
+};
+type EncodedSourceMapXInput = EncodedSourceMap & XInput;
+type DecodedSourceMapXInput = DecodedSourceMap & XInput;
+type SourceMapInput = string | EncodedSourceMapXInput | DecodedSourceMapXInput | TraceMap;
+declare abstract class SourceMap {
+    version: SourceMapV3['version'];
+    file: SourceMapV3['file'];
+    names: SourceMapV3['names'];
+    sourceRoot: SourceMapV3['sourceRoot'];
+    sources: SourceMapV3['sources'];
+    sourcesContent: SourceMapV3['sourcesContent'];
+    resolvedSources: SourceMapV3['sources'];
+    ignoreList: SourceMapV3['ignoreList'];
+}
+
+declare class TraceMap implements SourceMap {
+    version: SourceMapV3['version'];
+    file: SourceMapV3['file'];
+    names: SourceMapV3['names'];
+    sourceRoot: SourceMapV3['sourceRoot'];
+    sources: SourceMapV3['sources'];
+    sourcesContent: SourceMapV3['sourcesContent'];
+    ignoreList: SourceMapV3['ignoreList'];
+    resolvedSources: string[];
+    private _encoded;
+    private _decoded;
+    private _decodedMemo;
+    private _bySources;
+    private _bySourceMemos;
+    constructor(map: SourceMapInput, mapUrl?: string | null);
+}
+
+export type { DecodedSourceMap as D, EncodedSourceMap as E, SourceMapInput as S };