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/lucide-react/dist/esm/icons/lamp-ceiling.mjs

@@ -0,0 +1,24 @@
+/**
+ * @license lucide-react v1.24.0 - ISC
+ *
+ * This source code is licensed under the ISC license.
+ * See the LICENSE file in the root directory of this source tree.
+ */
+
+import createLucideIcon from '../createLucideIcon.mjs';
+
+const __iconNode = [
+  ["path", { d: "M12 2v5", key: "nd4vlx" }],
+  ["path", { d: "M14.829 15.998a3 3 0 1 1-5.658 0", key: "1pybiy" }],
+  [
+    "path",
+    {
+      d: "M20.92 14.606A1 1 0 0 1 20 16H4a1 1 0 0 1-.92-1.394l3-7A1 1 0 0 1 7 7h10a1 1 0 0 1 .92.606z",
+      key: "ma1wor"
+    }
+  ]
+];
+const LampCeiling = createLucideIcon("lamp-ceiling", __iconNode);
+
+export { __iconNode, LampCeiling as default };
+//# sourceMappingURL=lamp-ceiling.mjs.map