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/kayak.mjs

@@ -0,0 +1,25 @@
+/**
+ * @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 17a1 1 0 0 0-1 1v1a2 2 0 1 0 2-2z", key: "skzb1g" }],
+  [
+    "path",
+    {
+      d: "M20.97 3.61a.45.45 0 0 0-.58-.58C10.2 6.6 6.6 10.2 3.03 20.39a.45.45 0 0 0 .58.58C13.8 17.4 17.4 13.8 20.97 3.61",
+      key: "cv9jm7"
+    }
+  ],
+  ["path", { d: "m6.707 6.707 10.586 10.586", key: "d2l993" }],
+  ["path", { d: "M7 5a2 2 0 1 0-2 2h1a1 1 0 0 0 1-1z", key: "i0et4n" }]
+];
+const Kayak = createLucideIcon("kayak", __iconNode);
+
+export { __iconNode, Kayak as default };
+//# sourceMappingURL=kayak.mjs.map