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/feather.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: "M12.67 19a2 2 0 0 0 1.416-.588l6.154-6.172a6 6 0 0 0-8.49-8.49L5.586 9.914A2 2 0 0 0 5 11.328V18a1 1 0 0 0 1 1z",
+      key: "18jl4k"
+    }
+  ],
+  ["path", { d: "M16 8 2 22", key: "vp34q" }],
+  ["path", { d: "M17.5 15H9", key: "1oz8nu" }]
+];
+const Feather = createLucideIcon("feather", __iconNode);
+
+export { __iconNode, Feather as default };
+//# sourceMappingURL=feather.mjs.map