feat(consensus): consensus node delete command

Implement `solo-provisioner consensus node delete` command to remove a consensus node from the network.

Parent epic: #408
Depends on: #1044

### Context
Delete is the inverse of install/add. It removes the node from the network roster and cleans up its Kubernetes resources. Full design TBD — this ticket is a placeholder to track the requirement.

### Scope (preliminary — design TBD)
- `solo-provisioner consensus node delete --node-id [--namespace] [--orbit]`
- Remove node from network roster (DAB transaction or roster update)
- Delete ConsensusCapsule CR
- Optionally delete associated config CRs (scoped to this node)
- Optionally delete associated proxy CR
- Confirmation prompt before deletion (unless `--force`)

### Open questions
- Should config CRs be deleted or retained as audit trail (per HIP-1494 immutability)?
- Does the node need to be stopped first?
- How does roster removal work for a running network?

### Acceptance Criteria
- [ ] Design finalized
- [ ] Node removed from network roster
- [ ] ConsensusCapsule and associated resources cleaned up
- [ ] Confirmation prompt before destructive action