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/plug.mjs

@@ -0,0 +1,22 @@
+/**
+ * @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 22v-5", key: "1ega77" }],
+  ["path", { d: "M15 8V2", key: "18g5xt" }],
+  [
+    "path",
+    { d: "M17 8a1 1 0 0 1 1 1v4a4 4 0 0 1-4 4h-4a4 4 0 0 1-4-4V9a1 1 0 0 1 1-1z", key: "1xoxul" }
+  ],
+  ["path", { d: "M9 8V2", key: "14iosj" }]
+];
+const Plug = createLucideIcon("plug", __iconNode);
+
+export { __iconNode, Plug as default };
+//# sourceMappingURL=plug.mjs.map