Mirror of GitHub main kernel/user source onto the competition repo.
Main change: user/src/bin/init.rs three-tier run order (functional -> LTP -> perf/net) + per-group wall-clock watchdog, to stop musl perf groups from starving glibc + LTP of the 3600s budget. Also carries previously-unsynced kernel source already on GitHub main (signal_syscall.rs, devfs.rs, virtio/net.rs, process.rs).