move keyboard and mouse out of HAL into a standalone ps2.sys driver, implement usb stack with xhci controller discovery, hid keyboard/mouse, and bulk-only mass storage, add pci msi support with capability chain walking and software irq vector allocation (slots 16-23), rewrite user virtual memory as a USER_VA_REGION descriptor arena with per-process ownership tracking and guard page support, replacing the old bump allocator and top-down image region, add MmCreateUserRegion/MmDestroyAllUserRegions so process teardown reclaims all user va in one pass, allocate a pool-backed shadow framebuffer in hal_screen to fix cursor tearing and scroll corruption, reserve ap trampoline page below 1mb in uefi bootloader before boot services exit, rewrite memset/memcpy/memmove/memcmp with __stosq/__movsq intrinsics, promote driver flag literals to macros and add multi-tu STANDALONE_DRIVERS table to build.c, split rtl8139/rtl816x into header+source, rename KbReadScancode to KbReadKey, improve page fault output with MmDebugDescribeAddress and user region dump, fix %p to %016llX throughout.

code/user/syscall/syscall_stubs.asm

@@ -83,8 +83,8 @@ SYSCALL_STUB2 ApcReturn,            SYS_APC_RETURN
 ; ---------------------------------------------------------------------------
 PUBLIC SysUserApcDispatcher
 SysUserApcDispatcher PROC EXPORT
-    ; Kernel enters here with RSP pointing at SYS_USER_APC_FRAME.  There is no
-    ; return address because this is an IRET redirection.  Preserve RBX because
+    ; Kernel enters here with RSP pointing at SYS_USER_APC_FRAME. There is no
+    ; return address because this is an IRET redirection. Preserve RBX because
     ; the original user context resumes after SysApcReturn.
     push    rbx
     lea     rbx, [rsp + 8]          ; original injected RSP = frame pointer
@@ -183,7 +183,7 @@ SYSCALL_STUB6 ScreenPutChar,        SYS_SCREEN_PUT_CHAR
 SYSCALL_STUB2 KbPoll,               SYS_KB_POLL
 SYSCALL_STUB2 KbIsKeyDown,          SYS_KB_IS_KEY_DOWN
 SYSCALL_STUB2 KbReadChar,           SYS_KB_READ_CHAR
-SYSCALL_STUB2 KbReadScancode,       SYS_KB_READ_SCANCODE
+SYSCALL_STUB2 KbReadKey,            SYS_KB_READ_KEY
 SYSCALL_STUB2 KbGetModifiers,       SYS_KB_GET_MODIFIERS
 
 SYSCALL_STUB2 MousePoll,            SYS_MOUSE_POLL