Support search configuration

**Feature request**
It would be great to have notifications for services.

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

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

No files or tests are named. First trace how configuration options are defined and consumed, then clarify what “notifications for services” should trigger and how the new enable_notifications=false default should affect behavior. Done requires an agreed scope plus coverage for the configuration and notification behavior.

Written by the indexing model from the issue text.