Function render_editable_line 

pub fn render_editable_line(
    prefix: &str,
    buffer: &str,
    width: u16,
    theme: &dyn Palette,
) -> String

Render a single-line editable field with a visible block cursor.

prefix is rendered with the muted text colour, the editable buffer on a surface background, and the cursor in the configured cursor colour. The result spans width columns and the cursor is always visible, even when buffer is empty.