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/crown.mjs

@@ -0,0 +1,23 @@
+/**
+ * @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: "M11.562 3.266a.5.5 0 0 1 .876 0L15.39 8.87a1 1 0 0 0 1.516.294L21.183 5.5a.5.5 0 0 1 .798.519l-2.834 10.246a1 1 0 0 1-.956.734H5.81a1 1 0 0 1-.957-.734L2.02 6.02a.5.5 0 0 1 .798-.519l4.276 3.664a1 1 0 0 0 1.516-.294z",
+      key: "1vdc57"
+    }
+  ],
+  ["path", { d: "M5 21h14", key: "11awu3" }]
+];
+const Crown = createLucideIcon("crown", __iconNode);
+
+export { __iconNode, Crown as default };
+//# sourceMappingURL=crown.mjs.map