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/kanagawabones

@@ -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 = "#DDD8BB"
+background = "#1F1F28"
+# Selection colors
+selection-foreground = "#DDD8BB"
+selection-background = "#49473E"
+# Cursor colors
+cursor-color = "#E6E0C2"
+cursor-text = "#1F1F28"
+# The basic 16 colors
+# black
+palette = 0=#1F1F28
+palette = 8=#3C3C51
+# red
+palette = 1=#E46A78
+palette = 9=#EC818C
+# green
+palette = 2=#98BC6D
+palette = 10=#9EC967
+# yellow
+palette = 3=#E5C283
+palette = 11=#F1C982
+# blue
+palette = 4=#7EB3C9
+palette = 12=#7BC2DF
+# magenta
+palette = 5=#957FB8
+palette = 13=#A98FD2
+# cyan
+palette = 6=#7EB3C9
+palette = 14=#7BC2DF
+# white
+palette = 7=#DDD8BB
+palette = 15=#A8A48D