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/blocks.mjs

@@ -0,0 +1,23 @@
+/**
+ * @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 22V7a1 1 0 0 0-1-1H4a2 2 0 0 0-2 2v12a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-5a1 1 0 0 0-1-1H2",
+      key: "1ah6g2"
+    }
+  ],
+  ["rect", { x: "14", y: "2", width: "8", height: "8", rx: "1", key: "88lufb" }]
+];
+const Blocks = createLucideIcon("blocks", __iconNode);
+
+export { __iconNode, Blocks as default };
+//# sourceMappingURL=blocks.mjs.map