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/landmark.mjs

@@ -0,0 +1,27 @@
+/**
+ * @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 18v-7", key: "wt116b" }],
+  [
+    "path",
+    {
+      d: "M11.119 2.205a2 2 0 0 1 1.762 0l7.84 3.846A.5.5 0 0 1 20.5 7h-17a.5.5 0 0 1-.22-.949z",
+      key: "yxxwt6"
+    }
+  ],
+  ["path", { d: "M14 18v-7", key: "vav6t3" }],
+  ["path", { d: "M18 18v-7", key: "aexdmj" }],
+  ["path", { d: "M3 22h18", key: "8prr45" }],
+  ["path", { d: "M6 18v-7", key: "1ivflk" }]
+];
+const Landmark = createLucideIcon("landmark", __iconNode);
+
+export { __iconNode, Landmark as default };
+//# sourceMappingURL=landmark.mjs.map