Add TTL refresh interval and grace period configuration

## Goal
Allow setting TTL refresh interval and grace periods

## Description
Provide fine-grained control over TTL refresh timing to optimize Redis operations.

## Acceptance Criteria
- [ ] Add minimum refresh interval config
- [ ] Add grace period before expiry config
- [ ] Debounce rapid TTL updates
- [ ] Add tests for interval/grace configs
- [ ] Document configuration options