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/disc-3.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 = [
+  ["circle", { cx: "12", cy: "12", r: "10", key: "1mglay" }],
+  ["path", { d: "M6 12c0-1.7.7-3.2 1.8-4.2", key: "oqkarx" }],
+  ["circle", { cx: "12", cy: "12", r: "2", key: "1c9p78" }],
+  ["path", { d: "M18 12c0 1.7-.7 3.2-1.8 4.2", key: "1eah9h" }]
+];
+const Disc3 = createLucideIcon("disc-3", __iconNode);
+
+export { __iconNode, Disc3 as default };
+//# sourceMappingURL=disc-3.mjs.map