Feature: Make Ghostty the default terminal

Super+Return, $TERMINAL (rofi-sensible-terminal and scripts) and Thunar's
"Open Terminal Here" (exo helper + helpers.rc) now open Ghostty; foot stays
installed as the fallback. Also replaces Ghostty's deprecated
gtk-tabs-location = hidden with window-show-tab-bar = never.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -70,7 +70,7 @@ List of programs and tools I use.
 | Component         | Program    |
 |-------------------|------------|
 |🪟 Windows Manager | [hyprland](https://github.com/hyprwm/Hyprland)  |
-|🖥️ Terminal        | [foot](https://codeberg.org/dnkl/foot) / [ghostty](https://ghostty.org/) (system updater) |
+|🖥️ Terminal        | [ghostty](https://ghostty.org/) / [foot](https://codeberg.org/dnkl/foot) (fallback) |
 |🐚 Shell           | [zsh](https://github.com/ohmyzsh/ohmyzsh/wiki/Installing-ZSH) + oh-my-zsh / [oh-my-posh](https://ohmyposh.dev/) prompt (`.config/ohmyposh/zen.toml`) |
 |📁 File Manager    | [thunar](https://wiki.archlinux.org/title/Thunar)     |
 |📝 Editor          | [vs code](https://github.com/microsoft/vscode) / [neovim (changing to soon)](https://github.com/neovim/neovim)    |