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/database-check.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: "m16 19 2 2 4-4", key: "1b14m6" }],
+  ["path", { d: "M21 13.127V5", key: "59o5vz" }],
+  ["path", { d: "M3 12A9 3 0 0 0 21 12", key: "mv7ke4" }],
+  ["path", { d: "M3 5V19A9 3 0 0 0 13.318 21.968", key: "1lyu4j" }],
+  ["ellipse", { cx: "12", cy: "5", rx: "9", ry: "3", key: "msslwz" }]
+];
+const DatabaseCheck = createLucideIcon("database-check", __iconNode);
+
+export { __iconNode, DatabaseCheck as default };
+//# sourceMappingURL=database-check.mjs.map