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/2021/IntegerIndexedElementGet.js

@@ -0,0 +1,39 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+
+var GetValueFromBuffer = require('./GetValueFromBuffer');
+var IsValidIntegerIndex = require('./IsValidIntegerIndex');
+
+var typedArrayBuffer = require('typed-array-buffer');
+var typedArrayByteOffset = require('typed-array-byte-offset');
+var whichTypedArray = require('which-typed-array');
+
+var tableTAO = require('./tables/typed-array-objects');
+
+// https://262.ecma-international.org/12.0/#sec-integerindexedelementget
+
+module.exports = function IntegerIndexedElementGet(O, index) {
+	var arrayTypeName = whichTypedArray(O); // step 4
+	if (!arrayTypeName) {
+		throw new $TypeError('Assertion failed: `O` must be a TypedArray'); // step 1
+	}
+
+	if (typeof index !== 'number') {
+		throw new $TypeError('Assertion failed: `index` must be a Number');
+	}
+
+	if (!IsValidIntegerIndex(O, index)) {
+		return void undefined; // step 2
+	}
+
+	var offset = typedArrayByteOffset(O); // step 3
+
+	var elementType = tableTAO.name['$' + arrayTypeName]; // step 7
+
+	var elementSize = tableTAO.size['$' + elementType]; // step 5
+
+	var indexedPosition = (index * elementSize) + offset; // step 6
+
+	return GetValueFromBuffer(typedArrayBuffer(O), indexedPosition, elementType, true, 'Unordered'); // step 11
+};