power: proper shutdown via UEFI ResetSystem (ACPI S5)

- uefi.rs: full EFI_RUNTIME_SERVICES layout with reset_system at index 10
  (spec order); EfiResetSystem type + RESET_* constants
- power.rs: stash the runtime-services table pre-EBS; poweroff() calls
  ResetSystem(EfiResetShutdown) — still callable after ExitBootServices
  because we never call SetVirtualAddressMap, so the pointers keep
  working with physical addresses; falls back to the hlt loop
- shell: 'poweroff' and 'exit' shut the machine down (QEMU exits),
  'halt' keeps the plain hlt loop

1 files changed, 1 insertions, 0 deletions

diff --git a/rsnix/src/lib.rs b/rsnix/src/lib.rs
index d2dacf0..8c69b35 100644
--- a/rsnix/src/lib.rs
+++ b/rsnix/src/lib.rs
@@ -7,6 +7,7 @@ pub mod gop;
 pub mod interrupts;
 pub mod memory;
 pub mod paging;
+pub mod power;
 pub mod ps2;
 pub mod serial;
 pub mod uefi;