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/resolve/lib/normalize-options.js

@@ -0,0 +1,10 @@
+module.exports = function (x, opts) {
+    /**
+     * This file is purposefully a passthrough. It's expected that third-party
+     * environments will override it at runtime in order to inject special logic
+     * into `resolve` (by manipulating the options). One such example is the PnP
+     * code path in Yarn.
+     */
+
+    return opts || {};
+};