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/forestbones_dark

@@ -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 = "#E7DCC4"
+background = "#2C343A"
+# Selection colors
+selection-foreground = "#E7DCC4"
+selection-background = "#615B51"
+# Cursor colors
+cursor-color = "#EBE2CF"
+cursor-text = "#2C343A"
+# The basic 16 colors
+# black
+palette = 0=#2C343A
+palette = 8=#45525C
+# red
+palette = 1=#E67C7F
+palette = 9=#ED9294
+# green
+palette = 2=#A9C181
+palette = 10=#B0CE7B
+# yellow
+palette = 3=#DDBD7F
+palette = 11=#EDC77A
+# blue
+palette = 4=#7FBCB4
+palette = 12=#7AC9C0
+# magenta
+palette = 5=#D69AB7
+palette = 13=#E5A7C4
+# cyan
+palette = 6=#83C193
+palette = 14=#7DD093
+# white
+palette = 7=#E7DCC4
+palette = 15=#B2A790