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/2021/GetIterator.js

@@ -0,0 +1,63 @@
+'use strict';
+
+var GetIntrinsic = require('get-intrinsic');
+
+var $TypeError = require('es-errors/type');
+var $SyntaxError = require('es-errors/syntax');
+var isObject = require('es-object-atoms/isObject');
+var $asyncIterator = GetIntrinsic('%Symbol.asyncIterator%', true);
+
+var inspect = require('object-inspect');
+var hasSymbols = require('has-symbols')();
+
+var getIteratorMethod = require('../helpers/getIteratorMethod');
+var AdvanceStringIndex = require('./AdvanceStringIndex');
+var Call = require('./Call');
+var GetMethod = require('./GetMethod');
+
+var ES = {
+	AdvanceStringIndex: AdvanceStringIndex,
+	GetMethod: GetMethod
+};
+
+// https://262.ecma-international.org/9.0/#sec-getiterator
+
+module.exports = function GetIterator(obj, hint, method) {
+	var actualHint = hint;
+	if (arguments.length < 2) {
+		actualHint = 'sync';
+	}
+	if (actualHint !== 'sync' && actualHint !== 'async') {
+		throw new $TypeError("Assertion failed: `hint` must be one of 'sync' or 'async', got " + inspect(hint));
+	}
+
+	var actualMethod = method;
+	if (arguments.length < 3) {
+		if (actualHint === 'async') {
+			if (hasSymbols && $asyncIterator) {
+				actualMethod = GetMethod(obj, $asyncIterator);
+			}
+			if (typeof actualMethod === 'undefined') {
+				throw new $SyntaxError("async from sync iterators aren't currently supported");
+			}
+		} else {
+			actualMethod = getIteratorMethod(ES, obj);
+		}
+	}
+	var iterator = Call(actualMethod, obj);
+	if (!isObject(iterator)) {
+		throw new $TypeError('iterator must return an object');
+	}
+
+	return iterator;
+
+	// TODO: This should return an IteratorRecord
+	/*
+	var nextMethod = GetV(iterator, 'next');
+	return {
+		'[[Iterator]]': iterator,
+		'[[NextMethod]]': nextMethod,
+		'[[Done]]': false
+	};
+	*/
+};