Adds run-rvf.js that extracts the kernel from KERNEL_SEG, builds a
minimal initramfs with a static init binary, and boots via QEMU.
Rebuilds kernel with CONFIG_BLK_DEV_INITRD for initramfs support.
Modes: --boot (QEMU), --runtime (Node.js), --inspect (manifest)
Co-Authored-By: claude-flow <ruv@ruv.net>