feat: add d4r inference engines and Windows parity tooling

Add native K/M/RR inference engines, HIP kernels, replay and validation
harnesses, and Windows DLSS setup and runtime support. Include GPU
profiling tools, build and packaging scripts, platform integration
patches, and implementation documentation.

patches/optiscaler/0002-early-d3d12-command-backend.patch

@@ -0,0 +1,45 @@
+From 7ed1f1d66b430ba35a197fbd9880cd6a76af8f06 Mon Sep 17 00:00:00 2001
+From: Codex <codex@localhost>
+Date: Thu, 1 Oct 2026 16:45:01 +0300
+Subject: [PATCH] Install the external d4r command backend before NGX
+ initialization
+
+---
+ OptiScaler/hooks/D3D12_Hooks.cpp | 14 ++++++++++++++
+ 1 file changed, 14 insertions(+)
+
+diff --git a/OptiScaler/hooks/D3D12_Hooks.cpp b/OptiScaler/hooks/D3D12_Hooks.cpp
+index 29c0bec..3b757be 100644
+--- a/OptiScaler/hooks/D3D12_Hooks.cpp
++++ b/OptiScaler/hooks/D3D12_Hooks.cpp
+@@ -14,6 +14,7 @@
+ #include <proxies/IGDExt_Proxy.h>
+ #include <proxies/Streamline_Proxy.h>
+ #include <proxies/KernelBase_Proxy.h>
++#include <proxies/NVNGX_Proxy.h>
+ 
+ #include <detours/detours.h>
+ 
+@@ -2230,6 +2231,19 @@ static void HookToDevice(ID3D12Device* InDevice)
+     if (Util::CheckForRealObject(__FUNCTION__, InDevice, (IUnknown**) &realDevice))
+         pVTable = *(PVOID**) realDevice;
+ 
++    if (State::Instance().dlssExternalBackend)
++    {
++        // Capture command signatures/resources created before the game's NGX
++        // Init. Install before adding OptiScaler's own method trampolines.
++        using InstallCommandBackend = unsigned (*)(ID3D12Device*);
++        auto install = reinterpret_cast<InstallCommandBackend>(KernelBaseProxy::GetProcAddress_()(
++            NVNGXProxy::NVNGXModule(), "d4r_D3D12_InstallCommandBackend"));
++        auto result = install ? install(realDevice ? realDevice : InDevice) : 0;
++        LOG_INFO("External d4r command backend installed at device discovery: result={:X}", result);
++        if (result != 1)
++            LOG_ERROR("External d4r early command tracking failed; DLSS initialization must be checked");
++    }
++
+     // hudless
+     o_D3D12DeviceRelease = (PFN_Release) pVTable[2];
+     o_CreateSampler = (PFN_CreateSampler) pVTable[22];
+-- 
+2.55.0.windows.5
+