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/wind-arrow-down.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: "M10 2v8", key: "d4bbey" }],
+  ["path", { d: "M12.8 21.6A2 2 0 1 0 14 18H2", key: "19kp1d" }],
+  ["path", { d: "M17.5 10a2.5 2.5 0 1 1 2 4H2", key: "19kpjc" }],
+  ["path", { d: "m6 6 4 4 4-4", key: "k13n16" }]
+];
+const WindArrowDown = createLucideIcon("wind-arrow-down", __iconNode);
+
+export { __iconNode, WindArrowDown as default };
+//# sourceMappingURL=wind-arrow-down.mjs.map