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/monitor-speaker.mjs

@@ -0,0 +1,20 @@
+/**
+ * @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: "M5.5 20H8", key: "1k40s5" }],
+  ["path", { d: "M17 9h.01", key: "1j24nn" }],
+  ["rect", { width: "10", height: "16", x: "12", y: "4", rx: "2", key: "ixliua" }],
+  ["path", { d: "M8 6H4a2 2 0 0 0-2 2v6a2 2 0 0 0 2 2h4", key: "1mp6e1" }],
+  ["circle", { cx: "17", cy: "15", r: "1", key: "tqvash" }]
+];
+const MonitorSpeaker = createLucideIcon("monitor-speaker", __iconNode);
+
+export { __iconNode, MonitorSpeaker as default };
+//# sourceMappingURL=monitor-speaker.mjs.map