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/key-square.mjs

@@ -0,0 +1,30 @@
+/**
+ * @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: "M12.4 2.7a2.5 2.5 0 0 1 3.4 0l5.5 5.5a2.5 2.5 0 0 1 0 3.4l-3.7 3.7a2.5 2.5 0 0 1-3.4 0L8.7 9.8a2.5 2.5 0 0 1 0-3.4z",
+      key: "165ttr"
+    }
+  ],
+  ["path", { d: "m14 7 3 3", key: "1r5n42" }],
+  [
+    "path",
+    {
+      d: "m9.4 10.6-6.814 6.814A2 2 0 0 0 2 18.828V21a1 1 0 0 0 1 1h3a1 1 0 0 0 1-1v-1a1 1 0 0 1 1-1h1a1 1 0 0 0 1-1v-1a1 1 0 0 1 1-1h.172a2 2 0 0 0 1.414-.586l.814-.814",
+      key: "1ubxi2"
+    }
+  ]
+];
+const KeySquare = createLucideIcon("key-square", __iconNode);
+
+export { __iconNode, KeySquare as default };
+//# sourceMappingURL=key-square.mjs.map