feat: Add libghostty terminal backend (GPU-accelerated via Metal)

[ahmadyan]

Summary

Adds an experimental GPU-accelerated terminal backend using libghostty as an alternative to SwiftTerm.

• GPU-accelerated rendering via Metal for smooth, high-performance terminal output
• Full keyboard/mouse support including IME (Input Method Editor) for international input
• Settings integration with persistent "Use Ghostty Backend" toggle
• Clipboard support for copy/paste operations
• Terminal title/PWD tracking for tab titles

New Files

Path	Description
CodeEdit/Features/TerminalEmulator/Ghostty/	Core libghostty wrapper implementations
CodeEdit/Frameworks/GhosttyKit.xcframework/	Framework headers and metadata
scripts/setup-ghostty.sh	Build script for libghostty

Setup Required

The static library (~130MB) is not included in the repo due to GitHub size limits. To test:

# Build the GhosttyKit library
./scripts/setup-ghostty.sh

# Or copy from existing Ghostty build
cp /path/to/ghostty/macos/GhosttyKit.xcframework/macos-arm64/libghostty-fat.a \
   CodeEdit/Frameworks/GhosttyKit.xcframework/macos-arm64/

Usage

1. Run the setup script to get libghostty-fat.a
2. Build CodeEdit
3. Go to Settings → Terminal → Experimental
4. Enable "Use Ghostty Backend"
5. Restart CodeEdit

Test plan

• Build libghostty using setup script
• Build CodeEdit successfully
• Enable Ghostty backend in settings
• Verify setting persists after restart
• Test basic terminal operations (typing, running commands)
• Test keyboard shortcuts and special keys
• Test mouse scrolling and selection
• Test copy/paste operations

🤖 Generated with Claude Code