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/@babel/runtime/helpers/setFunctionName.js

@@ -0,0 +1,12 @@
+var _typeof = require("./typeof.js")["default"];
+function setFunctionName(e, t, n) {
+  "symbol" == _typeof(t) && (t = (t = t.description) ? "[" + t + "]" : "");
+  try {
+    Object.defineProperty(e, "name", {
+      configurable: !0,
+      value: n ? n + " " + t : t
+    });
+  } catch (e) {}
+  return e;
+}
+module.exports = setFunctionName, module.exports.__esModule = true, module.exports["default"] = module.exports;