Configure retention

Goal: Each stream has an appropriate lifecycle policy. Storage costs are controlled and/or aligned with regulatory / compliance retention requirements.

User sets retention periods per stream. For wired streams, parent retention cascades to children, override at child level when needed.

Why Streams: Replaces a fragmented setup (data stream lifecycle, ILM, index templates, index settings) with a single tab. Shows storage size, ingestion averages, and tier distribution in one view.