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/align-horizontal-space-between.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 = [
+  ["rect", { width: "6", height: "14", x: "3", y: "5", rx: "2", key: "j77dae" }],
+  ["rect", { width: "6", height: "10", x: "15", y: "7", rx: "2", key: "bq30hj" }],
+  ["path", { d: "M3 2v20", key: "1d2pfg" }],
+  ["path", { d: "M21 2v20", key: "p059bm" }]
+];
+const AlignHorizontalSpaceBetween = createLucideIcon("align-horizontal-space-between", __iconNode);
+
+export { __iconNode, AlignHorizontalSpaceBetween as default };
+//# sourceMappingURL=align-horizontal-space-between.mjs.map