Feature request: Allow customization of companion/buddy character

Feature Request

Is your feature request related to a problem?
The companion character (currently "Brinepoke" the cactus) that sits beside the input box is a nice touch, but there's no way to change or customize it.

Describe the solution you'd like
Add a setting (e.g., in ~/.claude/settings.json) to allow users to:

• Choose from a set of built-in companion characters
• Optionally disable the companion entirely

Something like:

{
  "companion": {
    "character": "brinepoke" | "other-character" | "none"
  }
}

Describe alternatives you've considered
Currently there is no workaround — the companion is hardcoded.

Additional context
This would be a small quality-of-life improvement that lets users personalize their Claude Code experience.