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/clipboard-copy.mjs

@@ -0,0 +1,20 @@
+/**
+ * @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 = [
+  ["rect", { width: "8", height: "4", x: "8", y: "2", rx: "1", ry: "1", key: "tgr4d6" }],
+  ["path", { d: "M8 4H6a2 2 0 0 0-2 2v14a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2v-2", key: "4jdomd" }],
+  ["path", { d: "M16 4h2a2 2 0 0 1 2 2v4", key: "3hqy98" }],
+  ["path", { d: "M21 14H11", key: "1bme5i" }],
+  ["path", { d: "m15 10-4 4 4 4", key: "5dvupr" }]
+];
+const ClipboardCopy = createLucideIcon("clipboard-copy", __iconNode);
+
+export { __iconNode, ClipboardCopy as default };
+//# sourceMappingURL=clipboard-copy.mjs.map