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/path-parse/README.md

@@ -0,0 +1,42 @@
+# path-parse [![Build Status](https://travis-ci.org/jbgutierrez/path-parse.svg?branch=master)](https://travis-ci.org/jbgutierrez/path-parse)
+
+> Node.js [`path.parse(pathString)`](https://nodejs.org/api/path.html#path_path_parse_pathstring) [ponyfill](https://ponyfill.com).
+
+## Install
+
+```
+$ npm install --save path-parse
+```
+
+## Usage
+
+```js
+var pathParse = require('path-parse');
+
+pathParse('/home/user/dir/file.txt');
+//=> {
+//       root : "/",
+//       dir : "/home/user/dir",
+//       base : "file.txt",
+//       ext : ".txt",
+//       name : "file"
+//   }
+```
+
+## API
+
+See [`path.parse(pathString)`](https://nodejs.org/api/path.html#path_path_parse_pathstring) docs.
+
+### pathParse(path)
+
+### pathParse.posix(path)
+
+The Posix specific version.
+
+### pathParse.win32(path)
+
+The Windows specific version.
+
+## License
+
+MIT © [Javier Blanco](http://jbgutierrez.info)