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/save-pen.mjs

@@ -0,0 +1,31 @@
+/**
+ * @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: "M13.33 13H8a1 1 0 00-1 1v7", key: "60fs50" }],
+  [
+    "path",
+    {
+      d: "M14.363 17.634a2 2 0 00-.506.854l-.837 2.87a.5.5 0 00.62.62l2.87-.837a2 2 0 00.854-.506l4.013-4.009a1 1 0 10-3.004-3.004z",
+      key: "dpj1he"
+    }
+  ],
+  ["path", { d: "M7 3v4a1 1 0 001 1h7", key: "vkun1b" }],
+  [
+    "path",
+    {
+      d: "M9 21H5a2 2 0 01-2-2V5a2 2 0 012-2h10.2a2 2 0 011.4.6l3.8 3.8a2 2 0 01.6 1.4v.3",
+      key: "1oj3yb"
+    }
+  ]
+];
+const SavePen = createLucideIcon("save-pen", __iconNode);
+
+export { __iconNode, SavePen as default };
+//# sourceMappingURL=save-pen.mjs.map