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/group.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 = [
+  ["path", { d: "M3 7V5c0-1.1.9-2 2-2h2", key: "adw53z" }],
+  ["path", { d: "M17 3h2c1.1 0 2 .9 2 2v2", key: "an4l38" }],
+  ["path", { d: "M21 17v2c0 1.1-.9 2-2 2h-2", key: "144t0e" }],
+  ["path", { d: "M7 21H5c-1.1 0-2-.9-2-2v-2", key: "rtnfgi" }],
+  ["rect", { width: "7", height: "5", x: "7", y: "7", rx: "1", key: "1eyiv7" }],
+  ["rect", { width: "7", height: "5", x: "10", y: "12", rx: "1", key: "1qlmkx" }]
+];
+const Group = createLucideIcon("group", __iconNode);
+
+export { __iconNode, Group as default };
+//# sourceMappingURL=group.mjs.map