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/caravan.mjs

@@ -0,0 +1,19 @@
+/**
+ * @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 19V9a4 4 0 0 0-4-4H6a4 4 0 0 0-4 4v8a2 2 0 0 0 2 2h2", key: "19jm3t" }],
+  ["path", { d: "M2 9h3a1 1 0 0 1 1 1v2a1 1 0 0 1-1 1H2", key: "13hakp" }],
+  ["path", { d: "M22 17v1a1 1 0 0 1-1 1H10v-9a1 1 0 0 1 1-1h2a1 1 0 0 1 1 1v9", key: "1crci8" }],
+  ["circle", { cx: "8", cy: "19", r: "2", key: "t8fc5s" }]
+];
+const Caravan = createLucideIcon("caravan", __iconNode);
+
+export { __iconNode, Caravan as default };
+//# sourceMappingURL=caravan.mjs.map