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/card-sim.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: "M12 14v4", key: "1thi36" }],
+  [
+    "path",
+    {
+      d: "M14.172 2a2 2 0 0 1 1.414.586l3.828 3.828A2 2 0 0 1 20 7.828V20a2 2 0 0 1-2 2H6a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2z",
+      key: "1o66bk"
+    }
+  ],
+  ["path", { d: "M8 14h8", key: "1fgep2" }],
+  ["rect", { x: "8", y: "10", width: "8", height: "8", rx: "1", key: "1aonk6" }]
+];
+const CardSim = createLucideIcon("card-sim", __iconNode);
+
+export { __iconNode, CardSim as default };
+//# sourceMappingURL=card-sim.mjs.map