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/clock-fading.mjs

@@ -0,0 +1,21 @@
+/**
+ * @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 2a10 10 0 0 1 7.38 16.75", key: "175t95" }],
+  ["path", { d: "M12 6v6l4 2", key: "mmk7yg" }],
+  ["path", { d: "M2.5 8.875a10 10 0 0 0-.5 3", key: "1vce0s" }],
+  ["path", { d: "M2.83 16a10 10 0 0 0 2.43 3.4", key: "o3fkw4" }],
+  ["path", { d: "M4.636 5.235a10 10 0 0 1 .891-.857", key: "1szpfk" }],
+  ["path", { d: "M8.644 21.42a10 10 0 0 0 7.631-.38", key: "9yhvd4" }]
+];
+const ClockFading = createLucideIcon("clock-fading", __iconNode);
+
+export { __iconNode, ClockFading as default };
+//# sourceMappingURL=clock-fading.mjs.map