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/regex.mjs

@@ -0,0 +1,22 @@
+/**
+ * @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: "M17 3v10", key: "15fgeh" }],
+  ["path", { d: "m12.67 5.5 8.66 5", key: "1gpheq" }],
+  ["path", { d: "m12.67 10.5 8.66-5", key: "1dkfa6" }],
+  [
+    "path",
+    { d: "M9 17a2 2 0 0 0-2-2H5a2 2 0 0 0-2 2v2a2 2 0 0 0 2 2h2a2 2 0 0 0 2-2v-2z", key: "swwfx4" }
+  ]
+];
+const Regex = createLucideIcon("regex", __iconNode);
+
+export { __iconNode, Regex as default };
+//# sourceMappingURL=regex.mjs.map