feat: add Ghostty terminal support (#225)

Add shipwright runner for Ghostty terminal emulator with example themes.

- Add ghostty.lua runner with Ghostty-specific color format
- Update init.lua to include ghostty in runner_files
- Add zenbones_dark and zenbones_light example themes

Ghostty uses a similar format to Kitty but with `=` separators and
`palette = N=COLOR` syntax for the 16 ANSI colors.

Tested and working with Ghostty terminal.

lua/zenbones/shipwright/init.lua

@@ -82,6 +82,7 @@ M.run = function()
 		"iterm",
 		"alacritty",
 		"kitty",
+		"ghostty",
 		"wezterm",
 		"tmux",
 		"windows_terminal",