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/cable-car.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 3h.01", key: "lbucoy" }],
+  ["path", { d: "M14 2h.01", key: "1k8aa1" }],
+  ["path", { d: "m2 9 20-5", key: "1kz0j5" }],
+  ["path", { d: "M12 12V6.5", key: "1vbrij" }],
+  ["rect", { width: "16", height: "10", x: "4", y: "12", rx: "3", key: "if91er" }],
+  ["path", { d: "M9 12v5", key: "3anwtq" }],
+  ["path", { d: "M15 12v5", key: "5xh3zn" }],
+  ["path", { d: "M4 17h16", key: "g4d7ey" }]
+];
+const CableCar = createLucideIcon("cable-car", __iconNode);
+
+export { __iconNode, CableCar as default };
+//# sourceMappingURL=cable-car.mjs.map