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/metronome.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 11.4V9.1", key: "audfby" }],
+  ["path", { d: "m12 17 6.59-6.59", key: "c0sb7j" }],
+  [
+    "path",
+    {
+      d: "m15.05 5.7-.218-.691a3 3 0 0 0-5.663 0L4.418 19.695A1 1 0 0 0 5.37 21h13.253a1 1 0 0 0 .951-1.31L18.45 16.2",
+      key: "1pkfrk"
+    }
+  ],
+  ["circle", { cx: "20", cy: "9", r: "2", key: "1udoqf" }]
+];
+const Metronome = createLucideIcon("metronome", __iconNode);
+
+export { __iconNode, Metronome as default };
+//# sourceMappingURL=metronome.mjs.map