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/neobones_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 = "#C6D5CF"
+background = "#0F191F"
+# Selection colors
+selection-foreground = "#C6D5CF"
+selection-background = "#3A3E3D"
+# Cursor colors
+cursor-color = "#CEDDD7"
+cursor-text = "#0F191F"
+# The basic 16 colors
+# black
+palette = 0=#0F191F
+palette = 8=#263945
+# red
+palette = 1=#DE6E7C
+palette = 9=#E8838F
+# green
+palette = 2=#90FF6B
+palette = 10=#A0FF85
+# yellow
+palette = 3=#B77E64
+palette = 11=#D68C67
+# blue
+palette = 4=#8190D4
+palette = 12=#92A0E2
+# magenta
+palette = 5=#B279A7
+palette = 13=#CF86C1
+# cyan
+palette = 6=#66A5AD
+palette = 14=#65B8C1
+# white
+palette = 7=#C6D5CF
+palette = 15=#98A39E