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/mail-question-mark.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: "M22 10.5V6a2 2 0 0 0-2-2H4a2 2 0 0 0-2 2v12c0 1.1.9 2 2 2h12.5", key: "e61zoh" }],
+  ["path", { d: "m22 7-8.97 5.7a1.94 1.94 0 0 1-2.06 0L2 7", key: "1ocrg3" }],
+  [
+    "path",
+    {
+      d: "M18 15.28c.2-.4.5-.8.9-1a2.1 2.1 0 0 1 2.6.4c.3.4.5.8.5 1.3 0 1.3-2 2-2 2",
+      key: "7z9rxb"
+    }
+  ],
+  ["path", { d: "M20 22v.01", key: "12bgn6" }]
+];
+const MailQuestionMark = createLucideIcon("mail-question-mark", __iconNode);
+
+export { __iconNode, MailQuestionMark as default };
+//# sourceMappingURL=mail-question-mark.mjs.map