When creating a new Buzz agent, the private key (nsec...) no longer appears

Previously, when creating a new agent, the private key (nsec...) would appear once to be stored locally.

Since today's update, that is no longer the case.

I require the private key in order to properly integrated buzz with hermes agent.

Start by reproducing the new-agent creation flow and compare it with the behavior before the latest update. Trace the Rust entry point responsible for displaying the generated private key; done means the nsec key appears once for local storage without weakening its handling.

Written by the indexing model from the issue text.