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/squares-subtract.mjs

@@ -0,0 +1,27 @@
+/**
+ * @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: "M10 22a2 2 0 0 1-2-2", key: "i7yj1i" }],
+  ["path", { d: "M16 22h-2", key: "18d249" }],
+  [
+    "path",
+    {
+      d: "M16 4a2 2 0 0 0-2-2H4a2 2 0 0 0-2 2v10a2 2 0 0 0 2 2h3a1 1 0 0 0 1-1v-5a2 2 0 0 1 2-2h5a1 1 0 0 0 1-1z",
+      key: "1njgbb"
+    }
+  ],
+  ["path", { d: "M20 8a2 2 0 0 1 2 2", key: "1770vt" }],
+  ["path", { d: "M22 14v2", key: "iot8ja" }],
+  ["path", { d: "M22 20a2 2 0 0 1-2 2", key: "qj8q6g" }]
+];
+const SquaresSubtract = createLucideIcon("squares-subtract", __iconNode);
+
+export { __iconNode, SquaresSubtract as default };
+//# sourceMappingURL=squares-subtract.mjs.map