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/2016/GetValueFromBuffer.js

@@ -0,0 +1,86 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $TypeError = require('es-errors/type');
+var $Uint8Array = GetIntrinsic('%Uint8Array%', true);
+
+var isInteger = require('math-intrinsics/isInteger');
+var callBound = require('call-bound');
+
+var $charAt = callBound('String.prototype.charAt');
+var $reverse = callBound('Array.prototype.reverse');
+var $slice = callBound('Array.prototype.slice');
+
+var bytesAsFloat32 = require('../helpers/bytesAsFloat32');
+var bytesAsFloat64 = require('../helpers/bytesAsFloat64');
+var bytesAsInteger = require('../helpers/bytesAsInteger');
+var defaultEndianness = require('../helpers/defaultEndianness');
+
+var IsDetachedBuffer = require('./IsDetachedBuffer');
+
+var isArrayBuffer = require('is-array-buffer');
+var safeConcat = require('safe-array-concat');
+
+var tableTAO = require('./tables/typed-array-objects');
+
+var isUnsignedElementType = function isUnsignedElementType(type) { return $charAt(type, 0) === 'U'; };
+
+// https://262.ecma-international.org/6.0/#sec-getvaluefrombuffer
+
+module.exports = function GetValueFromBuffer(arrayBuffer, byteIndex, type) {
+	if (!isArrayBuffer(arrayBuffer)) {
+		throw new $TypeError('Assertion failed: `arrayBuffer` must be an ArrayBuffer');
+	}
+
+	if (!isInteger(byteIndex)) {
+		throw new $TypeError('Assertion failed: `byteIndex` must be an integer');
+	}
+
+	if (typeof type !== 'string') {
+		throw new $TypeError('Assertion failed: `type` must be a string');
+	}
+
+	if (arguments.length > 3 && typeof arguments[3] !== 'boolean') {
+		throw new $TypeError('Assertion failed: `isLittleEndian` must be a boolean, if present');
+	}
+
+	if (IsDetachedBuffer(arrayBuffer)) {
+		throw new $TypeError('Assertion failed: ArrayBuffer is detached'); // step 1
+	}
+
+	// 2. Assert: There are sufficient bytes in arrayBuffer starting at byteIndex to represent a value of type.
+
+	if (byteIndex < 0) {
+		throw new $TypeError('Assertion failed: `byteIndex` must be non-negative'); // step 3
+	}
+
+	// 4. Let block be arrayBuffer’s [[ArrayBufferData]] internal slot.
+
+	var elementSize = tableTAO.size['$' + type]; // step 5
+	if (!elementSize) {
+		throw new $TypeError('Assertion failed: `type` must be one of ' + tableTAO.choices);
+	}
+
+	// 6. Let rawValue be a List of elementSize containing, in order, the elementSize sequence of bytes starting with block[byteIndex].
+	var rawValue = $slice(new $Uint8Array(arrayBuffer, byteIndex), 0, elementSize); // step 6
+
+	// 8. If isLittleEndian is not present, set isLittleEndian to either true or false. The choice is implementation dependent and should be the alternative that is most efficient for the implementation. An implementation must use the same value each time this step is executed and the same value must be used for the corresponding step in the SetValueInBuffer abstract operation.
+	var isLittleEndian = arguments.length > 3 ? arguments[3] : defaultEndianness === 'little'; // step 7
+
+	if (!isLittleEndian) {
+		$reverse(rawValue); // step 8
+	}
+
+	var bytes = $slice(safeConcat([0, 0, 0, 0, 0, 0, 0, 0], rawValue), -elementSize);
+
+	if (type === 'Float32') { // step 3
+		return bytesAsFloat32(bytes);
+	}
+
+	if (type === 'Float64') { // step 4
+		return bytesAsFloat64(bytes);
+	}
+
+	return bytesAsInteger(bytes, elementSize, isUnsignedElementType(type), false);
+};