Consider deprecating old middleware API

**Feature request**
It would be great to have search for types.

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

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

Start by locating the configuration handling and the search or type-discovery entry points; no files or tests are named. Clarify the mismatch between the title and body, then define the expected behavior of an `enable_search` option defaulting to false and add coverage showing the option's effect.

Written by the indexing model from the issue text.