Add rate limiting for notifications

**Description**
Currently api lacks proper import support.

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

**Priority**: Low/Medium

First reconcile the title's notification rate-limiting request with the body’s API import request, since they describe different work. After the scope is clarified, locate the relevant API entry point and configuration or tests; done should include the agreed configurable behavior, sensible defaults, and verification coverage.

Written by the indexing model from the issue text.