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/eraser.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: "M21 21H8a2 2 0 0 1-1.42-.587l-3.994-3.999a2 2 0 0 1 0-2.828l10-10a2 2 0 0 1 2.829 0l5.999 6a2 2 0 0 1 0 2.828L12.834 21",
+      key: "g5wo59"
+    }
+  ],
+  ["path", { d: "m5.082 11.09 8.828 8.828", key: "1wx5vj" }]
+];
+const Eraser = createLucideIcon("eraser", __iconNode);
+
+export { __iconNode, Eraser as default };
+//# sourceMappingURL=eraser.mjs.map