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/turtle.mjs

@@ -0,0 +1,25 @@
+/**
+ * @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: "m12 10 2 4v3a1 1 0 0 0 1 1h2a1 1 0 0 0 1-1v-3a8 8 0 1 0-16 0v3a1 1 0 0 0 1 1h2a1 1 0 0 0 1-1v-3l2-4h4Z",
+      key: "1lbbv7"
+    }
+  ],
+  ["path", { d: "M4.82 7.9 8 10", key: "m9wose" }],
+  ["path", { d: "M15.18 7.9 12 10", key: "p8dp2u" }],
+  ["path", { d: "M16.93 10H20a2 2 0 0 1 0 4H2", key: "12nsm7" }]
+];
+const Turtle = createLucideIcon("turtle", __iconNode);
+
+export { __iconNode, Turtle as default };
+//# sourceMappingURL=turtle.mjs.map