Convert Ghostty configuration to Termy

Produce a valid Termy config and a compatibility report. Never silently copy a Ghostty key into Termy merely because the names look similar.

Workflow

1. Locate the Ghostty input. Prefer an explicit path. Otherwise check:
   • $XDG_CONFIG_HOME/ghostty/config.ghostty
   • $XDG_CONFIG_HOME/ghostty/config
   • ~/.config/ghostty/config.ghostty
   • ~/.config/ghostty/config
   • macOS Application Support paths documented by Ghostty
2. Run the bundled converter: