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/cup-soda.mjs

@@ -0,0 +1,19 @@
+/**
+ * @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: "m6 8 1.75 12.28a2 2 0 0 0 2 1.72h4.54a2 2 0 0 0 2-1.72L18 8", key: "8166m8" }],
+  ["path", { d: "M5 8h14", key: "pcz4l3" }],
+  ["path", { d: "M7 15a6.47 6.47 0 0 1 5 0 6.47 6.47 0 0 0 5 0", key: "yjz344" }],
+  ["path", { d: "m12 8 1-6h2", key: "3ybfa4" }]
+];
+const CupSoda = createLucideIcon("cup-soda", __iconNode);
+
+export { __iconNode, CupSoda as default };
+//# sourceMappingURL=cup-soda.mjs.map