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/cloud-backup.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: "M21 15.251A4.5 4.5 0 0 0 17.5 8h-1.79A7 7 0 1 0 3 13.607", key: "xpoh9y" }],
+  ["path", { d: "M7 11v4h4", key: "q9yh32" }],
+  [
+    "path",
+    {
+      d: "M8 19a5 5 0 0 0 9-3 4.5 4.5 0 0 0-4.5-4.5 4.82 4.82 0 0 0-3.41 1.41L7 15",
+      key: "1xm8iu"
+    }
+  ]
+];
+const CloudBackup = createLucideIcon("cloud-backup", __iconNode);
+
+export { __iconNode, CloudBackup as default };
+//# sourceMappingURL=cloud-backup.mjs.map