Feature: Dynamic Cluster Membership (Joint Consensus)

[AnishMulay]

Allow adding/removing nodes at runtime using joint consensus semantics to maintain safety.

Scope

• Membership change entries in Raft log.
• Joint configuration phase handling.
• Update ClusterService discovery and gRPC peer set live.

Acceptance Criteria

• Safe add/remove under load with no lost commits.
• Leader transitions handled during membership changes.
• Integration tests: rolling scale up/down.

Notes

Gate with admin command (CLI) and dashboard control.