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/alarm-clock-minus.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 = [
+  ["circle", { cx: "12", cy: "13", r: "8", key: "3y4lt7" }],
+  ["path", { d: "M5 3 2 6", key: "18tl5t" }],
+  ["path", { d: "m22 6-3-3", key: "1opdir" }],
+  ["path", { d: "M6.38 18.7 4 21", key: "17xu3x" }],
+  ["path", { d: "M17.64 18.67 20 21", key: "kv2oe2" }],
+  ["path", { d: "M9 13h6", key: "1uhe8q" }]
+];
+const AlarmClockMinus = createLucideIcon("alarm-clock-minus", __iconNode);
+
+export { __iconNode, AlarmClockMinus as default };
+//# sourceMappingURL=alarm-clock-minus.mjs.map