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/link-2-off.mjs

@@ -0,0 +1,19 @@
+/**
+ * @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: "M9 17H7A5 5 0 0 1 7 7", key: "10o201" }],
+  ["path", { d: "M15 7h2a5 5 0 0 1 4 8", key: "1d3206" }],
+  ["line", { x1: "8", x2: "12", y1: "12", y2: "12", key: "rvw6j4" }],
+  ["line", { x1: "2", x2: "22", y1: "2", y2: "22", key: "a6p6uj" }]
+];
+const Link2Off = createLucideIcon("link-2-off", __iconNode);
+
+export { __iconNode, Link2Off as default };
+//# sourceMappingURL=link-2-off.mjs.map