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/rotate-3d.mjs

@@ -0,0 +1,18 @@
+/**
+ * @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: "m15.194 13.707 3.814 1.86-1.86 3.814", key: "16shm9" }],
+  ["path", { d: "M16.47214 7.52786 A 5 10 0 1 0 13 21.79796", key: "1245p8" }],
+  ["path", { d: "M21.79796 11 A 10 5 0 1 0 19 15.57071", key: "1i40ks" }]
+];
+const Rotate3d = createLucideIcon("rotate-3d", __iconNode);
+
+export { __iconNode, Rotate3d as default };
+//# sourceMappingURL=rotate-3d.mjs.map