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/dpc.h

@@ -0,0 +1,35 @@
+// Public nt-lite DDK deferred procedure call declarations.
+
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+#include <ntlite/ddk/list.h>
+#include <ntlite/ddk/sync.h>
+
+typedef struct KDPC KDPC;
+
+typedef void (*KDEFERRED_ROUTINE)(KDPC* dpc,
+                                  void* context,
+                                  void* systemArgument1,
+                                  void* systemArgument2);
+
+// Legacy DPC storage used by current kernel-mode drivers.
+struct KDPC {
+    LIST_ENTRY Link;
+    KDEFERRED_ROUTINE Routine;
+    void* Context;
+    void* SystemArgument1;
+    void* SystemArgument2;
+    volatile long Inserted;
+};
+
+// Initializes a DPC object.
+__declspec(dllexport) void KeInitializeDpc(KDPC* dpc,
+                                           KDEFERRED_ROUTINE routine,
+                                           void* context);
+
+// Queues a DPC if it is not already queued.
+__declspec(dllexport) bool KeInsertQueueDpc(KDPC* dpc,
+                                            void* systemArgument1,
+                                            void* systemArgument2);