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/power-off.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: "M18.36 6.64A9 9 0 0 1 20.77 15", key: "dxknvb" }],
+  ["path", { d: "M6.16 6.16a9 9 0 1 0 12.68 12.68", key: "1x7qb5" }],
+  ["path", { d: "M12 2v4", key: "3427ic" }],
+  ["path", { d: "m2 2 20 20", key: "1ooewy" }]
+];
+const PowerOff = createLucideIcon("power-off", __iconNode);
+
+export { __iconNode, PowerOff as default };
+//# sourceMappingURL=power-off.mjs.map