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.

engine/build.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+set -euo pipefail
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+OUT="${1:-$ROOT/build/native-engine}"
+CXX="${CXX:-g++}"
+mkdir -p "$OUT"
+# The native HIP network (hip_net.h) is shared by both runners when ROCm is installed; without it they fall back
+# to the engine's own Vulkan network. The library itself never links HIP.
+ROCM="${D4R_ROCM_DIR:-/opt/rocm}"
+HIP=()
+if [[ -f "$ROCM/include/hip/hip_runtime_api.h" ]]; then
+    HIP=(-DD4R_ENGINE_HIP "$ROOT/engine/hip_net.cpp" -I"$ROCM/include" -L"$ROCM/lib" -lamdhip64 "-Wl,-rpath,$ROCM/lib")
+fi
+"$CXX" -std=c++17 -O3 -Wall -Wextra -Wno-missing-field-initializers -fPIC -shared \
+    "$ROOT/engine/runtime.cpp" "$ROOT/engine/game.cpp" "$ROOT/engine/game_m.cpp" "$ROOT/engine/game_rr.cpp" -lvulkan -o "$OUT/libd4r_engine.so"
+"$CXX" -std=c++17 -O3 -Wall -Wextra -Wno-missing-field-initializers \
+    "$ROOT/engine/replay.cpp" "${HIP[@]}" -L"$OUT" -ld4r_engine -lvulkan '-Wl,-rpath,$ORIGIN' -o "$OUT/d4r-k"
+"$CXX" -std=c++17 -O3 -Wall -Wextra -Wno-missing-field-initializers \
+    "$ROOT/engine/replay_m.cpp" "${HIP[@]}" -L"$OUT" -ld4r_engine -lvulkan '-Wl,-rpath,$ORIGIN' -o "$OUT/d4r-m"
+"$CXX" -std=c++17 -O3 -Wall -Wextra -Wno-missing-field-initializers \
+    "$ROOT/engine/replay_rr.cpp" -L"$OUT" -ld4r_engine -lvulkan '-Wl,-rpath,$ORIGIN' -o "$OUT/d4r-rr"
+printf 'Built %s, %s and %s\n' "$OUT/d4r-k" "$OUT/d4r-m" "$OUT/d4r-rr"