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/bell-plus.mjs

@@ -0,0 +1,25 @@
+/**
+ * @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: "M10.268 21a2 2 0 0 0 3.464 0", key: "vwvbt9" }],
+  ["path", { d: "M15 8h6", key: "8ybuxh" }],
+  ["path", { d: "M18 5v6", key: "g5ayrv" }],
+  [
+    "path",
+    {
+      d: "M20.002 14.464a9 9 0 0 0 .738.863A1 1 0 0 1 20 17H4a1 1 0 0 1-.74-1.673C4.59 13.956 6 12.499 6 8a6 6 0 0 1 8.75-5.332",
+      key: "1abcvy"
+    }
+  ]
+];
+const BellPlus = createLucideIcon("bell-plus", __iconNode);
+
+export { __iconNode, BellPlus as default };
+//# sourceMappingURL=bell-plus.mjs.map