Apple Virtualization.framework backend for mvm.
On macOS (Apple Silicon), this crate uses objc2-virtualization to call
Virtualization.framework directly from Rust. VMs boot with VZLinuxBootLoader
using our Nix-built kernel + ext4 rootfs — same as Firecracker, sub-second
startup, no OCI, no XPC daemon, no Swift.
On other platforms, all functions return "not available" errors.