fix(cli): handle split and coalesced key input in choose() arrow navigation

Buffer the raw stdin stream and consume one recognized token at a time so
arrow-key navigation no longer silently drops keys when escape sequences are
split across data events or multiple keypresses are coalesced into one.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: dorlugasigal