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/superscript.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: "m4 19 8-8", key: "hr47gm" }],
+  ["path", { d: "m12 19-8-8", key: "1dhhmo" }],
+  [
+    "path",
+    {
+      d: "M20 12h-4c0-1.5.442-2 1.5-2.5S20 8.334 20 7.002c0-.472-.17-.93-.484-1.29a2.105 2.105 0 0 0-2.617-.436c-.42.239-.738.614-.899 1.06",
+      key: "1dfcux"
+    }
+  ]
+];
+const Superscript = createLucideIcon("superscript", __iconNode);
+
+export { __iconNode, Superscript as default };
+//# sourceMappingURL=superscript.mjs.map