Feature: Increase code editor font size

[damien-piedanna]

Hi, I made myself the same reflexion, so I modified /code/ui/src/index.css to add a scale for 21/9 screens

@media (min-width: 2560px) {
    :root {
        --scale: 1.5; /* Scale for 2K (2560x1440) */
    }
}