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/armchair.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: "M19 9V6a2 2 0 0 0-2-2H7a2 2 0 0 0-2 2v3", key: "irtipd" }],
+  [
+    "path",
+    {
+      d: "M3 16a2 2 0 0 0 2 2h14a2 2 0 0 0 2-2v-5a2 2 0 0 0-4 0v1.5a.5.5 0 0 1-.5.5h-9a.5.5 0 0 1-.5-.5V11a2 2 0 0 0-4 0z",
+      key: "1qyhux"
+    }
+  ],
+  ["path", { d: "M5 18v2", key: "ppbyun" }],
+  ["path", { d: "M19 18v2", key: "gy7782" }]
+];
+const Armchair = createLucideIcon("armchair", __iconNode);
+
+export { __iconNode, Armchair as default };
+//# sourceMappingURL=armchair.mjs.map