Add sync error logging, extend error flash, fix unload saves

- Log workforce sync errors to backend stdout so they appear in docker logs
- Extend error flash from 5s to 15s so errors are readable
- Replace sendBeacon (POST-only) with keepalive fetch (PUT) on unload —
  sendBeacon was hitting 404s on all three unload saves

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/node_modules/es-abstract/2023/SortIndexedProperties.js

@@ -0,0 +1,49 @@
+'use strict';
+
+var $TypeError = require('es-errors/type');
+var callBound = require('call-bound');
+var isInteger = require('math-intrinsics/isInteger');
+var isObject = require('es-object-atoms/isObject');
+
+var Get = require('./Get');
+var HasProperty = require('./HasProperty');
+var ToString = require('./ToString');
+
+var isAbstractClosure = require('../helpers/isAbstractClosure');
+
+var $sort = callBound('Array.prototype.sort');
+
+// https://262.ecma-international.org/14.0/#sec-sortindexedproperties
+
+module.exports = function SortIndexedProperties(obj, len, SortCompare, holes) {
+	if (!isObject(obj)) {
+		throw new $TypeError('Assertion failed: Type(obj) is not Object');
+	}
+	if (!isInteger(len) || len < 0) {
+		throw new $TypeError('Assertion failed: `len` must be an integer >= 0');
+	}
+	if (!isAbstractClosure(SortCompare) || SortCompare.length !== 2) {
+		throw new $TypeError('Assertion failed: `SortCompare` must be an abstract closure taking 2 arguments');
+	}
+	if (holes !== 'skip-holes' && holes !== 'read-through-holes') {
+		throw new $TypeError('Assertion failed: `holes` must be either ~skip-holes~ or ~read-through-holes~');
+	}
+
+	var items = []; // step 1
+
+	var k = 0; // step 2
+
+	while (k < len) { // step 3
+		var Pk = ToString(k);
+		var kRead = holes === 'skip-holes' ? HasProperty(obj, Pk) : true; // step 3.b - 3.c
+		if (kRead) { // step 3.d
+			var kValue = Get(obj, Pk);
+			items[items.length] = kValue;
+		}
+		k += 1; // step 3.e
+	}
+
+	$sort(items, SortCompare); // step 4
+
+	return items; // step 5
+};