[Streaming] Changefeed / CDC per Branch (Server-Sent Events or Redis PubSub)

[avelino]

Currently, clients must poll the API to detect changes. A changefeed system would allow real-time data synchronization and integrations with reactive systems.

Why
Modern architectures rely on Change Data Capture (CDC) for live updates. Implementing this natively positions ChronDB as a real-time source of truth.

What to do

• Implement changefeeds per branch:
  • REST: /changes?branch=main&since=<commit>
  • Redis: PUBLISH chrondb:changes:main {...}
• Support replay from specific commit.
• Optionally use Server-Sent Events (SSE) for streaming over HTTP.

Acceptance Criteria

• SSE endpoint streams commits in real time.
• Redis Pub/Sub integration working.
• Replay supported via since parameter.
• Examples documented.