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/hamburger.mjs

@@ -0,0 +1,25 @@
+/**
+ * @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 16H4a2 2 0 1 1 0-4h16a2 2 0 1 1 0 4h-4.25", key: "5dloqd" }],
+  ["path", { d: "M5 12a2 2 0 0 1-2-2 9 7 0 0 1 18 0 2 2 0 0 1-2 2", key: "1vl3my" }],
+  [
+    "path",
+    {
+      d: "M5 16a2 2 0 0 0-2 2 3 3 0 0 0 3 3h12a3 3 0 0 0 3-3 2 2 0 0 0-2-2q0 0 0 0",
+      key: "1us75o"
+    }
+  ],
+  ["path", { d: "m6.67 12 6.13 4.6a2 2 0 0 0 2.8-.4l3.15-4.2", key: "qqzweh" }]
+];
+const Hamburger = createLucideIcon("hamburger", __iconNode);
+
+export { __iconNode, Hamburger as default };
+//# sourceMappingURL=hamburger.mjs.map