Add rate limiting for filtering

**Feature request**
It would be great to have encryption for core.

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

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

First clarify whether this issue requests rate limiting for filtering or encryption for core, since the title and body describe different work. Then inspect the repository's configuration and filtering entry points; completion should include the requested config behavior with a default of false and a clear validation path.

Written by the indexing model from the issue text.