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/delete.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: "M10 5a2 2 0 0 0-1.344.519l-6.328 5.74a1 1 0 0 0 0 1.481l6.328 5.741A2 2 0 0 0 10 19h10a2 2 0 0 0 2-2V7a2 2 0 0 0-2-2z",
+      key: "1yo7s0"
+    }
+  ],
+  ["path", { d: "m12 9 6 6", key: "anjzzh" }],
+  ["path", { d: "m18 9-6 6", key: "1fp51s" }]
+];
+const Delete = createLucideIcon("delete", __iconNode);
+
+export { __iconNode, Delete as default };
+//# sourceMappingURL=delete.mjs.map