Keep the installer's build steps from reading its answers

Commands run during the install (distrobox, ssh) read stdin, so answers
typed ahead or piped in were swallowed and the questions fell back to their
defaults. Only the questions read stdin now.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

install.sh

@@ -23,13 +23,17 @@ for arg in "$@"; do
   esac
 done
 
+# Only the questions read from the terminal (or whatever stdin is); the build steps get
+# no input, so they can't swallow typed-ahead or piped answers.
+exec 3<&0 </dev/null
+
 step() { printf '\n\033[1m== %s\033[0m\n' "$*"; }
 ask() {  # ask "question" default(y|n)
   [ "$assume_yes" = 1 ] && [ "$2" = y ] && return 0
   [ "$assume_yes" = 1 ] && return 1
   local hint answer
   hint=$([ "$2" = y ] && echo "Y/n" || echo "y/N")
-  read -r -p "$1 [$hint] " answer
+  read -r -p "$1 [$hint] " answer <&3 || answer=
   answer=${answer:-$2}
   [[ $answer =~ ^[Yy] ]]
 }