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/test-tubes.mjs

@@ -0,0 +1,21 @@
+/**
+ * @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: "M9 2v17.5A2.5 2.5 0 0 1 6.5 22A2.5 2.5 0 0 1 4 19.5V2", key: "1hjrqt" }],
+  ["path", { d: "M20 2v17.5a2.5 2.5 0 0 1-2.5 2.5a2.5 2.5 0 0 1-2.5-2.5V2", key: "16lc8n" }],
+  ["path", { d: "M3 2h7", key: "7s29d5" }],
+  ["path", { d: "M14 2h7", key: "7sicin" }],
+  ["path", { d: "M9 16H4", key: "1bfye3" }],
+  ["path", { d: "M20 16h-5", key: "ddnjpe" }]
+];
+const TestTubes = createLucideIcon("test-tubes", __iconNode);
+
+export { __iconNode, TestTubes as default };
+//# sourceMappingURL=test-tubes.mjs.map