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/candy-cane.mjs

@@ -0,0 +1,26 @@
+/**
+ * @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: "m10.8 5 2.111 4.223", key: "11kb8w" }],
+  ["path", { d: "M17.75 7 15 2.1", key: "12x7e8" }],
+  ["path", { d: "m4.874 14.647 2.12 4.24", key: "ccpt4b" }],
+  [
+    "path",
+    {
+      d: "M5.7 21a2 2 0 0 1-3.5-2l8.6-14a6 6 0 0 1 10.4 6 2 2 0 1 1-3.464-2 2 2 0 1 0-3.464-2z",
+      key: "u5e8z4"
+    }
+  ],
+  ["path", { d: "m7.906 9.712 2.005 4.411", key: "1k0qph" }]
+];
+const CandyCane = createLucideIcon("candy-cane", __iconNode);
+
+export { __iconNode, CandyCane as default };
+//# sourceMappingURL=candy-cane.mjs.map