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/fan.mjs

@@ -0,0 +1,23 @@
+/**
+ * @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: "M10.827 16.379a6.082 6.082 0 0 1-8.618-7.002l5.412 1.45a6.082 6.082 0 0 1 7.002-8.618l-1.45 5.412a6.082 6.082 0 0 1 8.618 7.002l-5.412-1.45a6.082 6.082 0 0 1-7.002 8.618l1.45-5.412Z",
+      key: "484a7f"
+    }
+  ],
+  ["path", { d: "M12 12v.01", key: "u5ubse" }]
+];
+const Fan = createLucideIcon("fan", __iconNode);
+
+export { __iconNode, Fan as default };
+//# sourceMappingURL=fan.mjs.map