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/gem.mjs

@@ -0,0 +1,24 @@
+/**
+ * @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: "M10.5 3 8 9l4 13 4-13-2.5-6", key: "b3dvk1" }],
+  [
+    "path",
+    {
+      d: "M17 3a2 2 0 0 1 1.6.8l3 4a2 2 0 0 1 .013 2.382l-7.99 10.986a2 2 0 0 1-3.247 0l-7.99-10.986A2 2 0 0 1 2.4 7.8l2.998-3.997A2 2 0 0 1 7 3z",
+      key: "7w4byz"
+    }
+  ],
+  ["path", { d: "M2 9h20", key: "16fsjt" }]
+];
+const Gem = createLucideIcon("gem", __iconNode);
+
+export { __iconNode, Gem as default };
+//# sourceMappingURL=gem.mjs.map