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/lamp.mjs

@@ -0,0 +1,27 @@
+/**
+ * @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 12v6", key: "3ahymv" }],
+  [
+    "path",
+    {
+      d: "M4.077 10.615A1 1 0 0 0 5 12h14a1 1 0 0 0 .923-1.385l-3.077-7.384A2 2 0 0 0 15 2H9a2 2 0 0 0-1.846 1.23Z",
+      key: "1l7kg2"
+    }
+  ],
+  [
+    "path",
+    { d: "M8 20a2 2 0 0 1 2-2h4a2 2 0 0 1 2 2v1a1 1 0 0 1-1 1H9a1 1 0 0 1-1-1z", key: "1mmzpi" }
+  ]
+];
+const Lamp = createLucideIcon("lamp", __iconNode);
+
+export { __iconNode, Lamp as default };
+//# sourceMappingURL=lamp.mjs.map