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/jsx.js

@@ -0,0 +1,22 @@
+var REACT_ELEMENT_TYPE;
+function _createRawReactElement(e, r, E, l) {
+  REACT_ELEMENT_TYPE || (REACT_ELEMENT_TYPE = "function" == typeof Symbol && Symbol["for"] && Symbol["for"]("react.element") || 60103);
+  var o = e && e.defaultProps,
+    n = arguments.length - 3;
+  if (r || 0 === n || (r = {
+    children: void 0
+  }), 1 === n) r.children = l;else if (n > 1) {
+    for (var t = Array(n), f = 0; f < n; f++) t[f] = arguments[f + 3];
+    r.children = t;
+  }
+  if (r && o) for (var i in o) void 0 === r[i] && (r[i] = o[i]);else r || (r = o || {});
+  return {
+    $$typeof: REACT_ELEMENT_TYPE,
+    type: e,
+    key: void 0 === E ? null : "" + E,
+    ref: null,
+    props: r,
+    _owner: null
+  };
+}
+module.exports = _createRawReactElement, module.exports.__esModule = true, module.exports["default"] = module.exports;