Extends the amd64 headless screendump verification (99999 SCROLL-BACK
injected over the serial chardev socket, captured via QEMU's HMP
screendump over its monitor socket) to aarch64 (-device ramfb) and
riscv64 (-device ramfb) -- same script shape, no GUI or physical
typing needed on either. Both show the same deep-POST recovery
(Init: Mama birth..., HADES DoE rows 58-73, boot banner) and the same
pre-existing 4.4q live-cursor-draw glitch already confirmed on amd64,
present identically -- boot-mode scrollback is real and reachable on
every architecture, not just amd64.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
