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/2025/GeneratorValidate.js

@@ -0,0 +1,24 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var SLOT = require('internal-slot');
+
+// https://262.ecma-international.org/16.0/#sec-generatorvalidate
+
+module.exports = function GeneratorValidate(generator, generatorBrand) {
+	SLOT.assert(generator, '[[GeneratorState]]'); // step 1
+	SLOT.assert(generator, '[[GeneratorBrand]]'); // step 2
+
+	var brand = SLOT.get(generator, '[[GeneratorBrand]]');
+	if (brand !== generatorBrand) {
+		throw new $TypeError('Assertion failed: generator brand is unexpected: ' + brand);
+	}
+	SLOT.assert(generator, '[[GeneratorContext]]'); // step 4
+	var state = SLOT.get(generator, '[[GeneratorState]]'); // step 5
+	if (state === 'EXECUTING') {
+		throw new $TypeError('generator is executing');
+	}
+
+	return state; // step 7
+};