don't offer to install font if there is no curl

internal/wizard.zsh

@@ -245,6 +245,7 @@ function can_install_font() {
     return
   fi
   if [[ "$(uname)" == Darwin && $TERM_PROGRAM == iTerm.app ]]; then
+    (( $+commands[curl] )) || return
     [[ $TERM_PROGRAM_VERSION == [2-9]* ]] || return
     if [[ -f ~/Library/Fonts ]]; then
       [[ -d ~/Library/Fonts && -w ~/Library/Fonts ]] || return