introduce a stable NTL_DDK driver ABI to replace direct HAL_API and kernel-header access in drivers, add code/kernel/io_ddk.c and code/public/ntlite/ddk/ headers, change DriverEntry to take (const NTL_DDK*, NTL_DRIVER_INIT*), update kmain to build the DDK once via IoInitializeDdk/IoGetDdk and hand it to both boot and runtime drivers, downgrade code/public/ntlite/ddi/io_driver.h to a legacy I/O model header pulling from ntlite/ddk instead of kernel internals, move code/third_party/lwip into code/drivers/net/lwip/third_party, fix up lwip_sources.txt and build.c include paths to match, split build.c's single CFLAGS macro into COMMON/KERNEL/USER/BOOT/DRIVER cflags.

code/public/ntlite/ddk/semaphore.h

@@ -0,0 +1,29 @@
+// Public nt-lite DDK semaphore declarations.
+
+#pragma once
+
+#include <stdint.h>
+#include <ntlite/status.h>
+#include <ntlite/ddk/list.h>
+#include <ntlite/ddk/object.h>
+#include <ntlite/ddk/sync.h>
+
+typedef struct SEMAPHORE {
+    OBJECT Header;
+    SPINLOCK Lock;
+    int32_t Count;
+    int32_t MaxCount;
+    LIST_ENTRY WaitList;
+} SEMAPHORE;
+
+// Creates a counting semaphore.
+__declspec(dllexport) KSTATUS KeSemaphoreCreate(int32_t initial, int32_t max, SEMAPHORE** out);
+
+// Waits for a semaphore count to become available.
+__declspec(dllexport) KSTATUS KeWaitSemaphore(SEMAPHORE* semaphore);
+
+// Attempts to take a semaphore without blocking.
+__declspec(dllexport) KSTATUS KeTrySemaphore(SEMAPHORE* semaphore);
+
+// Releases one semaphore count.
+__declspec(dllexport) void KeSignalSemaphore(SEMAPHORE* semaphore);