Performs stream compaction based on retention policies.

This module is stateless and runs as Tasks under the TaskSupervisor. It calculates which messages need to be removed based on the stream's retention policy (max_age, max_messages, max_bytes) and performs the actual deletion.

How Compaction Works

1. Fetch stream metadata and retention policy
2. Calculate new earliest offset based on policy limits
3. Delete all messages before the new earliest offset
4. Update stream metadata with new earliest_offset and counters

Messages are removed when any of these conditions are met:

• max_age: Message timestamp is older than (now - max_age)
• max_messages: More than max_messages exist in the stream
• max_bytes: Total stream size exceeds max_bytes

The most aggressive limit (resulting in highest earliest_offset) wins.