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_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 = "#4F5B62"
+background = "#FAF3E1"
+# Selection colors
+selection-foreground = "#4F5B62"
+selection-background = "#D3DFE6"
+# Cursor colors
+cursor-color = "#4F5B62"
+cursor-text = "#FAF3E1"
+# The basic 16 colors
+# black
+palette = 0=#FAF3E1
+palette = 8=#DBC988
+# red
+palette = 1=#F85550
+palette = 9=#E6271C
+# green
+palette = 2=#8DA200
+palette = 10=#758700
+# yellow
+palette = 3=#DEA000
+palette = 11=#B98500
+# blue
+palette = 4=#3A94C4
+palette = 12=#297CA6
+# magenta
+palette = 5=#DF69BA
+palette = 13=#CA43A3
+# cyan
+palette = 6=#36A87E
+palette = 14=#258C67
+# white
+palette = 7=#4F5B62
+palette = 15=#6E7F88