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/badge-japanese-yen.mjs

@@ -0,0 +1,26 @@
+/**
+ * @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: "M3.85 8.62a4 4 0 0 1 4.78-4.77 4 4 0 0 1 6.74 0 4 4 0 0 1 4.78 4.78 4 4 0 0 1 0 6.74 4 4 0 0 1-4.77 4.78 4 4 0 0 1-6.75 0 4 4 0 0 1-4.78-4.77 4 4 0 0 1 0-6.76Z",
+      key: "3c2336"
+    }
+  ],
+  ["path", { d: "m9 8 3 3v7", key: "17yadx" }],
+  ["path", { d: "m12 11 3-3", key: "p4cfq1" }],
+  ["path", { d: "M9 12h6", key: "1c52cq" }],
+  ["path", { d: "M9 16h6", key: "8wimt3" }]
+];
+const BadgeJapaneseYen = createLucideIcon("badge-japanese-yen", __iconNode);
+
+export { __iconNode, BadgeJapaneseYen as default };
+//# sourceMappingURL=badge-japanese-yen.mjs.map