Add an accept_until helper that only sends "y" when a new [Y/n] prompt
appears in the tmux pane, replacing the fixed-count blind send loops that
could race ahead of prompts or send stray input. Resilient to changes in
the number of apply-phase prompts.
Relates to #51
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>