feat(syscall): implemented the reboot syscall with shutdown and reboot commands

[FlareCoding]

Note

Medium Risk
Exposes kernel power control to any caller that passes the standard Linux magic values, with no additional privilege gate visible in the new handler.

Overview
Adds the Linux reboot(2) syscall on both aarch64 and x86_64 (arch-specific syscall numbers) and wires it into the syscall table via a new sys_power handler.

The handler enforces Linux’s magic1/magic2 checks before acting on restart, power off, or halt commands—calling power::reboot() / power::shutdown() or entering an IRQ-off halt loop—and returns EOPNOTSUPP when restart/shutdown cannot complete on the platform.

Userland gains reboot and shutdown CLI utilities that invoke reboot(RB_AUTOBOOT), RB_POWER_OFF, and a halt fallback, and both apps are included in the applications build list.

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