Q#P1-P7: panels are buffers (a shared listview runtime module
generalizing the *buffer-list* idiom — zero protocol change, both
frontends render them for free); switch-in-place presentation with q
restore (the GPU cannot show splits); read-only via intercept with its
limits recorded; the Q#P6 round-trip buffer seam so semantic frontends
never optimistic-apply into panels (RET visits instead of inserting a
newline); references list, outline, minibuffer code-action picker,
hover-doc panel; byte==UTF-16 caveat inherited, not multiplied.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
