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/@babel/helper-validator-identifier/lib/index.js

@@ -0,0 +1,57 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+Object.defineProperty(exports, "isIdentifierChar", {
+  enumerable: true,
+  get: function () {
+    return _identifier.isIdentifierChar;
+  }
+});
+Object.defineProperty(exports, "isIdentifierName", {
+  enumerable: true,
+  get: function () {
+    return _identifier.isIdentifierName;
+  }
+});
+Object.defineProperty(exports, "isIdentifierStart", {
+  enumerable: true,
+  get: function () {
+    return _identifier.isIdentifierStart;
+  }
+});
+Object.defineProperty(exports, "isKeyword", {
+  enumerable: true,
+  get: function () {
+    return _keyword.isKeyword;
+  }
+});
+Object.defineProperty(exports, "isReservedWord", {
+  enumerable: true,
+  get: function () {
+    return _keyword.isReservedWord;
+  }
+});
+Object.defineProperty(exports, "isStrictBindOnlyReservedWord", {
+  enumerable: true,
+  get: function () {
+    return _keyword.isStrictBindOnlyReservedWord;
+  }
+});
+Object.defineProperty(exports, "isStrictBindReservedWord", {
+  enumerable: true,
+  get: function () {
+    return _keyword.isStrictBindReservedWord;
+  }
+});
+Object.defineProperty(exports, "isStrictReservedWord", {
+  enumerable: true,
+  get: function () {
+    return _keyword.isStrictReservedWord;
+  }
+});
+var _identifier = require("./identifier.js");
+var _keyword = require("./keyword.js");
+
+//# sourceMappingURL=index.js.map