runScoped<T> static method
Runs body with overrides merged on top of the effective config.
Only fields explicitly set in overrides are applied; nested option
objects are merged where appropriate.
Implementation
static T runScoped<T>(ConvertConfig overrides, T Function() body) {
final base = effective;
final merged = base._merge(overrides);
return runZoned(body, zoneValues: {_zoneKey: merged});
}