Xios desktop defaults

Installs the ambient desktop defaults that make the Xios X11 environment feel more like a small iOS Linux distro than a bag of packages.

It sets up rootless-friendly shell and XDG environment defaults, native iPad retina display profiles, Xft antialiasing and DPI resources, GTK3/GTK4 settings, UTF-8 locale defaults, touch-friendly cursor sizing, and runtime directories used by X11/GTK/Xfce/GNOME apps.

• Native profile: 2160x1620 at 264 DPI
• Comfy profile: 1440x1080 at 176 DPI
• Debug/VNC profile: 1024x768 at 96 DPI
• Ships a minimal real hicolor icon-theme index, so the GTK icon theme setting points at something installed
• Refreshes fontconfig, GSettings schemas, icon, MIME, and desktop databases when the relevant tools are present

Built for iPadOS/iOS rootless (palera1n/Dopamine, `/var/jb`).