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/@vitest/utils/dist/helpers.d.ts

@@ -0,0 +1,54 @@
+import { Nullable, Arrayable } from './types.js';
+
+interface CloneOptions {
+    forceWritable?: boolean;
+}
+interface ErrorOptions {
+    message?: string;
+    stackTraceLimit?: number;
+}
+/**
+ * Get original stacktrace without source map support the most performant way.
+ * - Create only 1 stack frame.
+ * - Rewrite prepareStackTrace to bypass "support-stack-trace" (usually takes ~250ms).
+ */
+declare function createSimpleStackTrace(options?: ErrorOptions): string;
+declare function notNullish<T>(v: T | null | undefined): v is NonNullable<T>;
+declare function assertTypes(value: unknown, name: string, types: string[]): void;
+declare function isPrimitive(value: unknown): boolean;
+declare function slash(path: string): string;
+declare function parseRegexp(input: string): RegExp;
+declare function toArray<T>(array?: Nullable<Arrayable<T>>): Array<T>;
+declare function isObject(item: unknown): boolean;
+declare function getType(value: unknown): string;
+declare function getOwnProperties(obj: any): (string | symbol)[];
+declare function deepClone<T>(val: T, options?: CloneOptions): T;
+declare function clone<T>(val: T, seen: WeakMap<any, any>, options?: CloneOptions): T;
+declare function noop(): void;
+declare function objectAttr(source: any, path: string, defaultValue?: undefined): any;
+type DeferPromise<T> = Promise<T> & {
+    resolve: (value: T | PromiseLike<T>) => void;
+    reject: (reason?: any) => void;
+};
+declare function createDefer<T>(): DeferPromise<T>;
+/**
+ * If code starts with a function call, will return its last index, respecting arguments.
+ * This will return 25 - last ending character of toMatch ")"
+ * Also works with callbacks
+ * ```
+ * toMatch({ test: '123' });
+ * toBeAliased('123')
+ * ```
+ */
+declare function getCallLastIndex(code: string): number | null;
+declare function isNegativeNaN(val: number): boolean;
+/**
+ * Deep merge :P
+ *
+ * Will merge objects only if they are plain
+ *
+ * Do not merge types - it is very expensive and usually it's better to case a type here
+ */
+declare function deepMerge<T extends object = object>(target: T, ...sources: any[]): T;
+
+export { type DeferPromise, assertTypes, clone, createDefer, createSimpleStackTrace, deepClone, deepMerge, getCallLastIndex, getOwnProperties, getType, isNegativeNaN, isObject, isPrimitive, noop, notNullish, objectAttr, parseRegexp, slash, toArray };