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/store.mjs

@@ -0,0 +1,24 @@
+/**
+ * @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: "M15 21v-5a1 1 0 0 0-1-1h-4a1 1 0 0 0-1 1v5", key: "slp6dd" }],
+  [
+    "path",
+    {
+      d: "M17.774 10.31a1.12 1.12 0 0 0-1.549 0 2.5 2.5 0 0 1-3.451 0 1.12 1.12 0 0 0-1.548 0 2.5 2.5 0 0 1-3.452 0 1.12 1.12 0 0 0-1.549 0 2.5 2.5 0 0 1-3.77-3.248l2.889-4.184A2 2 0 0 1 7 2h10a2 2 0 0 1 1.653.873l2.895 4.192a2.5 2.5 0 0 1-3.774 3.244",
+      key: "o0xfot"
+    }
+  ],
+  ["path", { d: "M4 10.95V19a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-8.05", key: "wn3emo" }]
+];
+const Store = createLucideIcon("store", __iconNode);
+
+export { __iconNode, Store as default };
+//# sourceMappingURL=store.mjs.map