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/piano.mjs

@@ -0,0 +1,27 @@
+/**
+ * @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: "M18.5 8c-1.4 0-2.6-.8-3.2-2A6.87 6.87 0 0 0 2 9v11a2 2 0 0 0 2 2h16a2 2 0 0 0 2-2v-8.5C22 9.6 20.4 8 18.5 8",
+      key: "lag0yf"
+    }
+  ],
+  ["path", { d: "M2 14h20", key: "myj16y" }],
+  ["path", { d: "M6 14v4", key: "9ng0ue" }],
+  ["path", { d: "M10 14v4", key: "1v8uk5" }],
+  ["path", { d: "M14 14v4", key: "1tqops" }],
+  ["path", { d: "M18 14v4", key: "18uqwm" }]
+];
+const Piano = createLucideIcon("piano", __iconNode);
+
+export { __iconNode, Piano as default };
+//# sourceMappingURL=piano.mjs.map