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/receipt-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: "m12 10 3-3", key: "1mc12w" }],
+  [
+    "path",
+    {
+      d: "M4 3a1 1 0 0 1 1-1 1.3 1.3 0 0 1 .7.2l.933.6a1.3 1.3 0 0 0 1.4 0l.934-.6a1.3 1.3 0 0 1 1.4 0l.933.6a1.3 1.3 0 0 0 1.4 0l.933-.6a1.3 1.3 0 0 1 1.4 0l.934.6a1.3 1.3 0 0 0 1.4 0l.933-.6A1.3 1.3 0 0 1 19 2a1 1 0 0 1 1 1v18a1 1 0 0 1-1 1 1.3 1.3 0 0 1-.7-.2l-.933-.6a1.3 1.3 0 0 0-1.4 0l-.934.6a1.3 1.3 0 0 1-1.4 0l-.933-.6a1.3 1.3 0 0 0-1.4 0l-.933.6a1.3 1.3 0 0 1-1.4 0l-.934-.6a1.3 1.3 0 0 0-1.4 0l-.933.6a1.3 1.3 0 0 1-.7.2 1 1 0 0 1-1-1z",
+      key: "ycz6yz"
+    }
+  ],
+  ["path", { d: "M9 11h6", key: "1fldmi" }],
+  ["path", { d: "M9 15h6", key: "cctwl0" }],
+  ["path", { d: "m9 7 3 3v7", key: "1x0cue" }]
+];
+const ReceiptJapaneseYen = createLucideIcon("receipt-japanese-yen", __iconNode);
+
+export { __iconNode, ReceiptJapaneseYen as default };
+//# sourceMappingURL=receipt-japanese-yen.mjs.map