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-minus.mjs

@@ -0,0 +1,24 @@
+/**
+ * @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: "M16.243 3.757A6 6 0 0 0 6 8c0 4.499-1.411 5.956-2.738 7.326A1 1 0 0 0 4 17h16a1 1 0 0 0 .74-1.673A9.4 9.4 0 0 1 18.667 12",
+      key: "bdwj86"
+    }
+  ]
+];
+const BellMinus = createLucideIcon("bell-minus", __iconNode);
+
+export { __iconNode, BellMinus as default };
+//# sourceMappingURL=bell-minus.mjs.map