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/copy-minus.mjs

@@ -0,0 +1,18 @@
+/**
+ * @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 = [
+  ["line", { x1: "12", x2: "18", y1: "15", y2: "15", key: "1nscbv" }],
+  ["rect", { width: "14", height: "14", x: "8", y: "8", rx: "2", ry: "2", key: "17jyea" }],
+  ["path", { d: "M4 16c-1.1 0-2-.9-2-2V4c0-1.1.9-2 2-2h10c1.1 0 2 .9 2 2", key: "zix9uf" }]
+];
+const CopyMinus = createLucideIcon("copy-minus", __iconNode);
+
+export { __iconNode, CopyMinus as default };
+//# sourceMappingURL=copy-minus.mjs.map