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/expand.mjs

@@ -0,0 +1,23 @@
+/**
+ * @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: "m15 15 6 6", key: "1s409w" }],
+  ["path", { d: "m15 9 6-6", key: "ko1vev" }],
+  ["path", { d: "M21 16v5h-5", key: "1ck2sf" }],
+  ["path", { d: "M21 8V3h-5", key: "1qoq8a" }],
+  ["path", { d: "M3 16v5h5", key: "1t08am" }],
+  ["path", { d: "m3 21 6-6", key: "wwnumi" }],
+  ["path", { d: "M3 8V3h5", key: "1ln10m" }],
+  ["path", { d: "M9 9 3 3", key: "v551iv" }]
+];
+const Expand = createLucideIcon("expand", __iconNode);
+
+export { __iconNode, Expand as default };
+//# sourceMappingURL=expand.mjs.map