Support timeout configuration

**Feature request**
It would be great to have import for validation.

**Use case**
Many users need this functionality for production deployments.

**Implementation idea**
Add a new config option `enable_import` with default `false`.

First resolve the mismatch between the title, which requests timeout configuration, and the body, which requests import for validation via enable_import. Then locate the configuration handling and validation-import entry points, confirm how defaults are represented, and verify that the selected behavior is disabled by default and works when enabled.

Written by the indexing model from the issue text.