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-justify-center.mjs

@@ -0,0 +1,21 @@
+/**
+ * @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: "2", y: "5", rx: "2", key: "dy24zr" }],
+  ["rect", { width: "6", height: "10", x: "16", y: "7", rx: "2", key: "13zkjt" }],
+  ["path", { d: "M12 2v20", key: "t6zp3m" }]
+];
+const AlignHorizontalJustifyCenter = createLucideIcon(
+  "align-horizontal-justify-center",
+  __iconNode
+);
+
+export { __iconNode, AlignHorizontalJustifyCenter as default };
+//# sourceMappingURL=align-horizontal-justify-center.mjs.map