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/chess-king.mjs

@@ -0,0 +1,28 @@
+/**
+ * @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: "M4 20a2 2 0 0 1 2-2h12a2 2 0 0 1 2 2v1a1 1 0 0 1-1 1H5a1 1 0 0 1-1-1z", key: "mqzwx6" }
+  ],
+  [
+    "path",
+    {
+      d: "m6.7 18-1-1C4.35 15.682 3 14.09 3 12a5 5 0 0 1 4.95-5c1.584 0 2.7.455 4.05 1.818C13.35 7.455 14.466 7 16.05 7A5 5 0 0 1 21 12c0 2.082-1.359 3.673-2.7 5l-1 1",
+      key: "1gdt1g"
+    }
+  ],
+  ["path", { d: "M10 4h4", key: "1xpv9s" }],
+  ["path", { d: "M12 2v6.818", key: "b17a49" }]
+];
+const ChessKing = createLucideIcon("chess-king", __iconNode);
+
+export { __iconNode, ChessKing as default };
+//# sourceMappingURL=chess-king.mjs.map