feat(kernel,gui): NT I/O Manager (IRP-based drivers) + Registry Editor

Kernel (NT I/O subsystem):
- kernel/nt/io.c + include/kernel/nt/io.h (new): DRIVER_OBJECTs with a
  MajorFunction dispatch table, DEVICE_OBJECTs that can be stacked (attached),
  and IRPs pushed down the stack via io_call_driver / completed with
  io_complete_request. Ships three demo drivers: \Driver\Null (write sink,
  EOF reads), \Driver\Zero (zero-filled reads), and \Driver\Monitor -- a filter
  attached above \Device\Null that counts and forwards each IRP down the stack.
  Wired into the [12/14] boot step.
- LazyBox `iodev` lists drivers/devices with the stack and IRP counters, then
  runs a live demo: a WRITE IRP through the filtered Null stack and a READ from
  the Zero device.

GUI:
- gui/gui_apps.c: "Registry Editor" -- navigate the NT \Registry hive tree,
  click subkeys to descend and ".." to go up, with a values pane showing each
  value's name/type/data. Registered in the app table (start menu).

Verified live in the GUI terminal (screenshotted): 3 drivers / 3 devices, the
NullMonitor->Null device stack, a 16-byte WRITE sunk through the filter
(status 0x0), and an 8-byte zeroed READ from \Device\Zero. Clean build on
x86_64/aarch64/armv8i; 0 panics / 0 OOM.

Co-Authored-By: Claude Opus 4.8 <[email protected]>
Claude-Session: https://claude.ai/code/session_01Fh5z6V7nGPbHvqVG5p4CXX

Makefile

@@ -125,7 +125,7 @@ CORE_SRCS = kernel/main.c kernel/task.c kernel/sync.c kernel/timer.c kernel/prin
             kernel/panic.c kernel/trace.c kernel/sched.c kernel/cron.c kernel/syscall.c \
             kernel/syslog.c kernel/module.c kernel/kobject.c kernel/metrics.c kernel/namespace.c \
             kernel/signal.c kernel/workqueue.c kernel/tsc.c kernel/vt_art.c \
-            kernel/sub/sub_runtime.c kernel/sub/sub_vm.c kernel/nt/ob.c kernel/nt/reg.c \
+            kernel/sub/sub_runtime.c kernel/sub/sub_vm.c kernel/nt/ob.c kernel/nt/reg.c kernel/nt/io.c \
             kernel/wait.c kernel/futex.c kernel/rcu.c kernel/ktest.c \
             kernel/elf.c kernel/exec.c \
             lib/string.c lib/vsprintf.c lib/bitmap.c lib/rbtree.c lib/kfifo.c lib/hashtable.c lib/font8x8.c \