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/square-dashed.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: "M5 3a2 2 0 0 0-2 2", key: "y57alp" }],
+  ["path", { d: "M19 3a2 2 0 0 1 2 2", key: "18rm91" }],
+  ["path", { d: "M21 19a2 2 0 0 1-2 2", key: "1j7049" }],
+  ["path", { d: "M5 21a2 2 0 0 1-2-2", key: "sbafld" }],
+  ["path", { d: "M9 3h1", key: "1yesri" }],
+  ["path", { d: "M9 21h1", key: "15o7lz" }],
+  ["path", { d: "M14 3h1", key: "1ec4yj" }],
+  ["path", { d: "M14 21h1", key: "v9vybs" }],
+  ["path", { d: "M3 9v1", key: "1r0deq" }],
+  ["path", { d: "M21 9v1", key: "mxsmne" }],
+  ["path", { d: "M3 14v1", key: "vnatye" }],
+  ["path", { d: "M21 14v1", key: "169vum" }]
+];
+const SquareDashed = createLucideIcon("square-dashed", __iconNode);
+
+export { __iconNode, SquareDashed as default };
+//# sourceMappingURL=square-dashed.mjs.map