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/nut.mjs

@@ -0,0 +1,30 @@
+/**
+ * @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: "M12 4V2", key: "1k5q1u" }],
+  [
+    "path",
+    {
+      d: "M5 10v4a7.004 7.004 0 0 0 5.277 6.787c.412.104.802.292 1.102.592L12 22l.621-.621c.3-.3.69-.488 1.102-.592A7.003 7.003 0 0 0 19 14v-4",
+      key: "1tgyif"
+    }
+  ],
+  [
+    "path",
+    {
+      d: "M12 4C8 4 4.5 6 4 8c-.243.97-.919 1.952-2 3 1.31-.082 1.972-.29 3-1 .54.92.982 1.356 2 2 1.452-.647 1.954-1.098 2.5-2 .595.995 1.151 1.427 2.5 2 1.31-.621 1.862-1.058 2.5-2 .629.977 1.162 1.423 2.5 2 1.209-.548 1.68-.967 2-2 1.032.916 1.683 1.157 3 1-1.297-1.036-1.758-2.03-2-3-.5-2-4-4-8-4Z",
+      key: "tnsqj"
+    }
+  ]
+];
+const Nut = createLucideIcon("nut", __iconNode);
+
+export { __iconNode, Nut as default };
+//# sourceMappingURL=nut.mjs.map