Add rate limiting for encryption

**Description**
Currently core lacks proper notifications support.

**Proposed solution**
Add configurable notifications with sensible defaults.

**Priority**: Low/Medium

The title requests rate limiting for encryption, while the description proposes configurable notifications, so first clarify which behavior is intended. No files, tests, or entry points are named; locate the relevant core encryption or notification entry point, then confirm the expected defaults and a testable completion condition before starting.

Written by the indexing model from the issue text.