Enable banner by default over stderr

[pvdz]

This enables the Socket ascii art banner at the top of every command and help screen.

It looks roughly like this:

   _____         _       _        /---------------
  |   __|___ ___| |_ ___| |_      | Socket.dev CLI ver 0.14.57:a70bc02:72eb3827:dev
  |__   | . |  _| '_| -_|  _|     | Node: v20.18.2, API token set: 19tED
  |_____|___|___|_,_|___|_|.dev   | Command: `socket`, cwd: ~/socket/socket-cli

This banner contains versioning, login status, command executed (without flags), and the cwd.

This will help us with debugging when people include this in their report.

The banner is emitted over stderr (just like the spinner) and should not interfere with output that's meant to be piped through.