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/ajv/dist/vocabularies/jtd/properties.d.ts

@@ -0,0 +1,22 @@
+import type { CodeKeywordDefinition, ErrorObject, KeywordErrorDefinition, SchemaObject } from "../../types";
+import type { KeywordCxt } from "../../compile/validate";
+import { _JTDTypeError } from "./error";
+declare enum PropError {
+    Additional = "additional",
+    Missing = "missing"
+}
+type PropKeyword = "properties" | "optionalProperties";
+type PropSchema = {
+    [P in string]?: SchemaObject;
+};
+export type JTDPropertiesError = _JTDTypeError<PropKeyword, "object", PropSchema> | ErrorObject<PropKeyword, {
+    error: PropError.Additional;
+    additionalProperty: string;
+}, PropSchema> | ErrorObject<PropKeyword, {
+    error: PropError.Missing;
+    missingProperty: string;
+}, PropSchema>;
+export declare const error: KeywordErrorDefinition;
+declare const def: CodeKeywordDefinition;
+export declare function validateProperties(cxt: KeywordCxt): void;
+export default def;