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-get/README.md

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+# es-abstract-get <sup>[![Version Badge][npm-version-svg]][package-url]</sup>
+
+[![github actions][actions-image]][actions-url]
+[![coverage][codecov-image]][codecov-url]
+[![License][license-image]][license-url]
+[![Downloads][downloads-image]][downloads-url]
+
+[![npm badge][npm-badge-png]][package-url]
+
+The ECMAScript “getting properties” abstract operations — [`Get`][Get], [`GetV`][GetV], and [`GetMethod`][GetMethod] — plus the [`isPropertyKey`][isPropertyKey] helper they share, with TypeScript types.
+
+## Motivation
+
+These operations are also available in [`es-abstract`][es-abstract],
+but `es-abstract` ships every abstract operation for every spec edition,
+so depending on it to use one or two of them pulls in a very large dependency graph.
+These three operations (and `isPropertyKey`) historically never differ between spec editions,
+so they’re split out here:
+a package that only needs `Get`, `GetV`, `GetMethod`, or `isPropertyKey` can depend on this instead and get a far smaller install.
+
+Each operation is its own entry point - there is intentionally no main (`.`) export - so you only pay for what you import.
+
+## Example
+
+```js
+var Get = require('es-abstract-get/Get');
+var GetV = require('es-abstract-get/GetV');
+var GetMethod = require('es-abstract-get/GetMethod');
+var isPropertyKey = require('es-abstract-get/isPropertyKey');
+var assert = require('assert');
+
+// Get(O, P): O must be an Object
+assert.equal(Get({ a: 1 }, 'a'), 1);
+
+// GetV(V, P): V may be a primitive (it is coerced to an object for the lookup,
+// but the original value is the receiver)
+assert.equal(GetV('abc', 'length'), 3);
+
+// GetMethod(O, P): returns undefined for null/undefined, throws if not callable
+assert.equal(GetMethod({}, 'toString'), Object.prototype.toString);
+assert.equal(GetMethod({ a: null }, 'a'), undefined);
+
+// isPropertyKey(argument): true for strings and symbols
+assert.equal(isPropertyKey('a'), true);
+assert.equal(isPropertyKey(Symbol.iterator), true);
+assert.equal(isPropertyKey(1), false);
+```
+
+## Tests
+Simply clone the repo, `npm install`, and run `npm test`
+
+[package-url]: https://npmjs.org/package/es-abstract-get
+[npm-version-svg]: https://versionbadg.es/ljharb/es-abstract-get.svg
+[npm-badge-png]: https://nodei.co/npm/es-abstract-get.png?downloads=true&stars=true
+[license-image]: https://img.shields.io/npm/l/es-abstract-get.svg
+[license-url]: LICENSE
+[downloads-image]: https://img.shields.io/npm/dm/es-abstract-get.svg
+[downloads-url]: https://npm-stat.com/charts.html?package=es-abstract-get
+[codecov-image]: https://codecov.io/gh/ljharb/es-abstract-get/branch/main/graphs/badge.svg
+[codecov-url]: https://app.codecov.io/gh/ljharb/es-abstract-get/
+[actions-image]: https://img.shields.io/github/check-runs/ljharb/es-abstract-get/main
+[actions-url]: https://github.com/ljharb/es-abstract-get/actions
+[es-abstract]: https://npmjs.org/package/es-abstract
+[Get]: https://tc39.es/ecma262/#sec-get-o-p
+[GetV]: https://tc39.es/ecma262/#sec-getv
+[GetMethod]: https://tc39.es/ecma262/#sec-getmethod
+[isPropertyKey]: https://tc39.es/ecma262/#sec-ispropertykey