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/waves-arrow-down.mjs

@@ -0,0 +1,31 @@
+/**
+ * @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 10L12 2", key: "jvb0aw" }],
+  ["path", { d: "M16 6L12 10L8 6", key: "9j6vje" }],
+  [
+    "path",
+    {
+      d: "M2 15C2.6 15.5 3.2 16 4.5 16C7 16 7 14 9.5 14C12.1 14 11.9 16 14.5 16C17 16 17 14 19.5 14C20.8 14 21.4 14.5 22 15",
+      key: "s2zepw"
+    }
+  ],
+  [
+    "path",
+    {
+      d: "M2 21C2.6 21.5 3.2 22 4.5 22C7 22 7 20 9.5 20C12.1 20 11.9 22 14.5 22C17 22 17 20 19.5 20C20.8 20 21.4 20.5 22 21",
+      key: "u68omc"
+    }
+  ]
+];
+const WavesArrowDown = createLucideIcon("waves-arrow-down", __iconNode);
+
+export { __iconNode, WavesArrowDown as default };
+//# sourceMappingURL=waves-arrow-down.mjs.map