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/cake.mjs

@@ -0,0 +1,24 @@
+/**
+ * @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: "M20 21v-8a2 2 0 0 0-2-2H6a2 2 0 0 0-2 2v8", key: "1w3rig" }],
+  ["path", { d: "M4 16s.5-1 2-1 2.5 2 4 2 2.5-2 4-2 2.5 2 4 2 2-1 2-1", key: "n2jgmb" }],
+  ["path", { d: "M2 21h20", key: "1nyx9w" }],
+  ["path", { d: "M7 8v3", key: "1qtyvj" }],
+  ["path", { d: "M12 8v3", key: "hwp4zt" }],
+  ["path", { d: "M17 8v3", key: "1i6e5u" }],
+  ["path", { d: "M7 4h.01", key: "1bh4kh" }],
+  ["path", { d: "M12 4h.01", key: "1ujb9j" }],
+  ["path", { d: "M17 4h.01", key: "1upcoc" }]
+];
+const Cake = createLucideIcon("cake", __iconNode);
+
+export { __iconNode, Cake as default };
+//# sourceMappingURL=cake.mjs.map