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/file-box.mjs

@@ -0,0 +1,32 @@
+/**
+ * @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: "M14.5 22H18a2 2 0 0 0 2-2V8a2.4 2.4 0 0 0-.706-1.706l-3.588-3.588A2.4 2.4 0 0 0 14 2H6a2 2 0 0 0-2 2v3.8",
+      key: "1kchwa"
+    }
+  ],
+  ["path", { d: "M14 2v5a1 1 0 0 0 1 1h5", key: "wfsgrz" }],
+  ["path", { d: "M11.7 14.2 7 17l-4.7-2.8", key: "1yk8tc" }],
+  [
+    "path",
+    {
+      d: "M3 13.1a2 2 0 0 0-.999 1.76v3.24a2 2 0 0 0 .969 1.78L6 21.7a2 2 0 0 0 2.03.01L11 19.9a2 2 0 0 0 1-1.76V14.9a2 2 0 0 0-.97-1.78L8 11.3a2 2 0 0 0-2.03-.01z",
+      key: "19flxy"
+    }
+  ],
+  ["path", { d: "M7 17v5", key: "1yj1jh" }]
+];
+const FileBox = createLucideIcon("file-box", __iconNode);
+
+export { __iconNode, FileBox as default };
+//# sourceMappingURL=file-box.mjs.map