test: expand smoke suite to 89 tests + fix SMP orphan reparenting

test: expand smoke suite to 89 tests + fix SMP orphan reparenting

New userspace tests in init.c:
- E1: setuid/setgid/seteuid/setegid credential manipulation
- E2: fcntl F_GETFL/F_SETFL (O_NONBLOCK toggle)
- E3: fcntl F_GETFD/F_SETFD (FD_CLOEXEC)
- E4: sigsuspend (block SIGUSR1, self-signal, sigsuspend unblocks)
- E5: orphan reparenting (grandchild reparented to init after middle exits)
- Boot-time LZ4 Frame decompression pattern check

Kernel fix — SMP orphan reparenting:
- process_exit_notify() hardcoded parent_pid=1 for reparenting, but with
  SMP the AP idle processes consume PIDs 1-3 before the init userspace
  process is created (PID 4+).
- Added sched_set_init_pid() to register the actual init process PID.
- arch_platform.c calls sched_set_init_pid(current_process->pid) before
  entering userspace, so orphan reparenting targets the correct process.

89/89 smoke tests pass (9s), cppcheck clean.