Inline Completion with completion-preview-mode

As part of the ongoing overhaul of my Emacs setup I’ve been trying to make the most of the built-in functionality that recent Emacs releases keep quietly shipping. My in-buffer completion setup is based on corfu and cape these days, but it turns out I had overlooked a nice Emacs 30 addition in the same area - completion-preview-mode. It gives you inline completion suggestions - the “ghost text” UI…