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/ampersands.mjs

@@ -0,0 +1,29 @@
+/**
+ * @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 17c-5-3-7-7-7-9a2 2 0 0 1 4 0c0 2.5-5 2.5-5 6 0 1.7 1.3 3 3 3 2.8 0 5-2.2 5-5",
+      key: "12lh1k"
+    }
+  ],
+  [
+    "path",
+    {
+      d: "M22 17c-5-3-7-7-7-9a2 2 0 0 1 4 0c0 2.5-5 2.5-5 6 0 1.7 1.3 3 3 3 2.8 0 5-2.2 5-5",
+      key: "173c68"
+    }
+  ]
+];
+const Ampersands = createLucideIcon("ampersands", __iconNode);
+
+export { __iconNode, Ampersands as default };
+//# sourceMappingURL=ampersands.mjs.map