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/es-abstract/2024/MakeFullYear.js

@@ -0,0 +1,26 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var ToIntegerOrInfinity = require('./ToIntegerOrInfinity');
+
+var isNaN = require('math-intrinsics/isNaN');
+
+// https://262.ecma-international.org/15.0/#sec-makefullyear
+
+module.exports = function MakeFullYear(year) {
+	if (typeof year !== 'number') {
+		throw new $TypeError('Assertion failed: `year` must be a Number');
+	}
+
+	if (isNaN(year)) {
+		return NaN; // step 1
+	}
+
+	var truncated = ToIntegerOrInfinity(year); // step 2
+	if (0 <= truncated && truncated <= 99) {
+		return 1900 + truncated; // step 3
+	}
+
+	return truncated; // step 4
+};