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/calendar-heart.mjs

@@ -0,0 +1,29 @@
+/**
+ * @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: "M12.127 22H5a2 2 0 0 1-2-2V6a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2v5.125", key: "vxdnp4" }
+  ],
+  [
+    "path",
+    {
+      d: "M14.62 18.8A2.25 2.25 0 1 1 18 15.836a2.25 2.25 0 1 1 3.38 2.966l-2.626 2.856a.998.998 0 0 1-1.507 0z",
+      key: "15cy7q"
+    }
+  ],
+  ["path", { d: "M16 2v4", key: "4m81vk" }],
+  ["path", { d: "M3 10h18", key: "8toen8" }],
+  ["path", { d: "M8 2v4", key: "1cmpym" }]
+];
+const CalendarHeart = createLucideIcon("calendar-heart", __iconNode);
+
+export { __iconNode, CalendarHeart as default };
+//# sourceMappingURL=calendar-heart.mjs.map