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/table-columns-split.mjs

@@ -0,0 +1,26 @@
+/**
+ * @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: "M14 14v2", key: "w2a1xv" }],
+  ["path", { d: "M14 20v2", key: "1lq872" }],
+  ["path", { d: "M14 2v2", key: "6buw04" }],
+  ["path", { d: "M14 8v2", key: "i67w9a" }],
+  ["path", { d: "M2 15h8", key: "82wtch" }],
+  ["path", { d: "M2 3h6a2 2 0 0 1 2 2v14a2 2 0 0 1-2 2H2", key: "up0l64" }],
+  ["path", { d: "M2 9h8", key: "yelfik" }],
+  ["path", { d: "M22 15h-4", key: "1es58f" }],
+  ["path", { d: "M22 3h-2a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h2", key: "pdjoqf" }],
+  ["path", { d: "M22 9h-4", key: "1luja7" }],
+  ["path", { d: "M5 3v18", key: "14hmio" }]
+];
+const TableColumnsSplit = createLucideIcon("table-columns-split", __iconNode);
+
+export { __iconNode, TableColumnsSplit as default };
+//# sourceMappingURL=table-columns-split.mjs.map