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.

extras/ghostty/tokyobones_light

@@ -0,0 +1,37 @@
+# This file is auto-generated by shipwright.nvim
+# Ghostty color configuration
+# See: https://ghostty.org/docs/config/reference
+# Basic colors
+foreground = "#333A57"
+background = "#D6D7DC"
+# Selection colors
+selection-foreground = "#333A57"
+selection-background = "#BBC0D8"
+# Cursor colors
+cursor-color = "#333A57"
+cursor-text = "#D6D7DC"
+# The basic 16 colors
+# black
+palette = 0=#D6D7DC
+palette = 8=#ADB0BD
+# red
+palette = 1=#8B4351
+palette = 9=#7E3242
+# green
+palette = 2=#34645D
+palette = 10=#26554F
+# yellow
+palette = 3=#8F5E14
+palette = 11=#794E0D
+# blue
+palette = 4=#34548C
+palette = 12=#26467A
+# magenta
+palette = 5=#5A4A79
+palette = 13=#503875
+# cyan
+palette = 6=#176775
+palette = 14=#34645D
+# white
+palette = 7=#333A57
+palette = 15=#56618D