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/shovel.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: "M21.56 4.56a1.5 1.5 0 0 1 0 2.122l-.47.47a3 3 0 0 1-4.212-.03 3 3 0 0 1 0-4.243l.44-.44a1.5 1.5 0 0 1 2.121 0z",
+      key: "1gcedi"
+    }
+  ],
+  [
+    "path",
+    {
+      d: "M3 22a1 1 0 0 1-1-1v-3.586a1 1 0 0 1 .293-.707l3.355-3.355a1.205 1.205 0 0 1 1.704 0l3.296 3.296a1.205 1.205 0 0 1 0 1.704l-3.355 3.355a1 1 0 0 1-.707.293z",
+      key: "pg9kv3"
+    }
+  ],
+  ["path", { d: "m9 15 7.879-7.878", key: "1o1zgh" }]
+];
+const Shovel = createLucideIcon("shovel", __iconNode);
+
+export { __iconNode, Shovel as default };
+//# sourceMappingURL=shovel.mjs.map