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/vector-square.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: "M19.5 7a24 24 0 0 1 0 10", key: "8n60xe" }],
+  ["path", { d: "M4.5 7a24 24 0 0 0 0 10", key: "2lmadr" }],
+  ["path", { d: "M7 19.5a24 24 0 0 0 10 0", key: "1q94o2" }],
+  ["path", { d: "M7 4.5a24 24 0 0 1 10 0", key: "2z8ypa" }],
+  ["rect", { x: "17", y: "17", width: "5", height: "5", rx: "1", key: "1ac74s" }],
+  ["rect", { x: "17", y: "2", width: "5", height: "5", rx: "1", key: "1e7h5j" }],
+  ["rect", { x: "2", y: "17", width: "5", height: "5", rx: "1", key: "1t4eah" }],
+  ["rect", { x: "2", y: "2", width: "5", height: "5", rx: "1", key: "940dhs" }]
+];
+const VectorSquare = createLucideIcon("vector-square", __iconNode);
+
+export { __iconNode, VectorSquare as default };
+//# sourceMappingURL=vector-square.mjs.map