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/scale-3d.mjs

@@ -0,0 +1,19 @@
+/**
+ * @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: "M5 7v11a1 1 0 0 0 1 1h11", key: "13dt1j" }],
+  ["path", { d: "M5.293 18.707 11 13", key: "ezgbsx" }],
+  ["circle", { cx: "19", cy: "19", r: "2", key: "17f5cg" }],
+  ["circle", { cx: "5", cy: "5", r: "2", key: "1gwv83" }]
+];
+const Scale3d = createLucideIcon("scale-3d", __iconNode);
+
+export { __iconNode, Scale3d as default };
+//# sourceMappingURL=scale-3d.mjs.map