feat: add Ghostty terminal configuration

[tctibbs]

Add configuration support for Ghostty terminal.

Ghostty

• https://ghostty.org / https://github.com/ghostty-org/ghostty
• Fast, native terminal emulator written in Zig
• GPU-accelerated rendering
• Native platform integration (macOS, Linux)
• Minimal, focused feature set
• Growing community adoption

Current Setup

• Primary: WezTerm with custom config (theme, tabs, background)

Tasks

• Create ghostty/ config directory
• Add Ghostty config with Catppuccin theme
• Add install.sh for symlinks
• Add to Brewfile (if available via brew)
• Update README

Notes

• May coexist with WezTerm as alternative
• Evaluate as potential WezTerm replacement