cmux terminfo overlay

cmux ships Ghostty's xterm-ghostty terminfo entry, but the embedded renderer in cmux has differed from Ghostty's app renderer in how it treats the "bright" SGR 90-97/100-107 sequences.

This overlay patches the terminfo capabilities so that tput setaf 8 (and similar "bright" colors) uses 256-color indexed sequences (38;5;<n>m / 48;5;<n>m) rather than SGR 90-97/100-107. This avoids relying on bright SGR handling and fixes zsh-autosuggestions (default fg=8) visibility issues in cmux.

The build phase Copy Ghostty Resources overlays this directory onto the app bundle's Contents/Resources/terminfo after copying Ghostty's resources.