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/shuffle.mjs

@@ -0,0 +1,20 @@
+/**
+ * @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: "m18 14 4 4-4 4", key: "10pe0f" }],
+  ["path", { d: "m18 2 4 4-4 4", key: "pucp1d" }],
+  ["path", { d: "M2 18h1.973a4 4 0 0 0 3.3-1.7l5.454-8.6a4 4 0 0 1 3.3-1.7H22", key: "1ailkh" }],
+  ["path", { d: "M2 6h1.972a4 4 0 0 1 3.6 2.2", key: "km57vx" }],
+  ["path", { d: "M22 18h-6.041a4 4 0 0 1-3.3-1.8l-.359-.45", key: "os18l9" }]
+];
+const Shuffle = createLucideIcon("shuffle", __iconNode);
+
+export { __iconNode, Shuffle as default };
+//# sourceMappingURL=shuffle.mjs.map