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/case-upper.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 11h4.5a1 1 0 0 1 0 5h-4a.5.5 0 0 1-.5-.5v-9a.5.5 0 0 1 .5-.5h3a1 1 0 0 1 0 5",
+      key: "nxs35"
+    }
+  ],
+  ["path", { d: "m2 16 4.039-9.69a.5.5 0 0 1 .923 0L11 16", key: "d5nyq2" }],
+  ["path", { d: "M3.304 13h6.392", key: "1q3zxz" }]
+];
+const CaseUpper = createLucideIcon("case-upper", __iconNode);
+
+export { __iconNode, CaseUpper as default };
+//# sourceMappingURL=case-upper.mjs.map