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/paintbrush-vertical.mjs

@@ -0,0 +1,25 @@
+/**
+ * @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: "M10 2v2", key: "7u0qdc" }],
+  ["path", { d: "M14 2v4", key: "qmzblu" }],
+  ["path", { d: "M17 2a1 1 0 0 1 1 1v9H6V3a1 1 0 0 1 1-1z", key: "ycvu00" }],
+  [
+    "path",
+    {
+      d: "M6 12a1 1 0 0 0-1 1v1a2 2 0 0 0 2 2h2a1 1 0 0 1 1 1v2.9a2 2 0 1 0 4 0V17a1 1 0 0 1 1-1h2a2 2 0 0 0 2-2v-1a1 1 0 0 0-1-1",
+      key: "iw4wnp"
+    }
+  ]
+];
+const PaintbrushVertical = createLucideIcon("paintbrush-vertical", __iconNode);
+
+export { __iconNode, PaintbrushVertical as default };
+//# sourceMappingURL=paintbrush-vertical.mjs.map