Add TypeScript types for validation

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

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

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

The issue names no files, tests, or entry points. Start by locating the handler configuration and existing config options, then reconcile the title's TypeScript validation reference with the request for handler search. Done should include a clearly defined search behavior and an `enable_search` option whose default is `false`.

Written by the indexing model from the issue text.