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/zodiac-libra.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: "M3 16h6.857c.162-.012.19-.323.038-.38a6 6 0 1 1 4.212 0c-.153.057-.125.368.038.38H21",
+      key: "1novf0"
+    }
+  ],
+  ["path", { d: "M3 20h18", key: "1l19wn" }]
+];
+const ZodiacLibra = createLucideIcon("zodiac-libra", __iconNode);
+
+export { __iconNode, ZodiacLibra as default };
+//# sourceMappingURL=zodiac-libra.mjs.map