penguin: add native mmap aperture MMIO hooks

[lacraig2]

Summary

• add a small exported MMIO region API for Penguin-owned QEMU mappings
• generate the new CFFI declarations from the Penguin QEMU header surface
• install the aperture with low overlap priority so existing machine MMIO keeps precedence

Testing

• ninja -C qemu/build-kvm libqemu-kvm-x86_64.so
• ninja -C qemu/build-system libqemu-system-intel64.so libqemu-system-armel.so libqemu-system-aarch64.so libqemu-system-mipsel.so libqemu-system-mipseb.so libqemu-system-mips64el.so libqemu-system-mips64eb.so libqemu-system-powerpc.so libqemu-system-powerpc64.so libqemu-system-powerpc64le.so libqemu-system-riscv64.so libqemu-system-loongarch64.so
• validated downstream with the focused Penguin native mmap smoke and legacy devfs/procfs mmap tests