Optimize components for large datasets

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

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

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

Start by locating the configuration handling and handler import entry points in the Shell-based terminal agent. Check how existing options are defined and how handlers are loaded. Done means a disabled-by-default enable_import option controls handler importing and is documented or covered by the repository's existing checks.

Written by the indexing model from the issue text.