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/syringe.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: "m18 2 4 4", key: "22kx64" }],
+  ["path", { d: "m17 7 3-3", key: "1w1zoj" }],
+  ["path", { d: "M19 9 8.7 19.3c-1 1-2.5 1-3.4 0l-.6-.6c-1-1-1-2.5 0-3.4L15 5", key: "1exhtz" }],
+  ["path", { d: "m9 11 4 4", key: "rovt3i" }],
+  ["path", { d: "m5 19-3 3", key: "59f2uf" }],
+  ["path", { d: "m14 4 6 6", key: "yqp9t2" }]
+];
+const Syringe = createLucideIcon("syringe", __iconNode);
+
+export { __iconNode, Syringe as default };
+//# sourceMappingURL=syringe.mjs.map