Introduces the ability to explicitly block a peer via the node control socket. Previously, the node only exposed follow and unfollow commands. While the underlying policy database schema supported a Block variant, there was no mechanism to trigger this state via the client handle.

The new block command:

1. Updates the node’s follow policy to Block.
2. Immediately disconnects the peer if a session is active.
3. Prevents future inbound and outbound connections to that peer.
4. Filters the peer out of the available peers list.

REVIEW

Changes:

• Squash review commits into their respective parents
• Split the changes between adding the command and making changes to the service
• Emit Event::PeerDisconnected instead of Event::PeerConnected in Service::connected, when peer is blocked
• Adds fix to test harness code to allow for the case of a blocked peer

Rebase