[INFRA] Import NVIDIA/CCCL upstream as optimization reference library

CCCL (CUDA C++ Core Libraries) provides:
- CUB: device/block/warp-level GPU primitives (reduce, scan, sort, topk)
- Thrust: high-level parallel algorithms (transform_reduce, sort, scan)
- libcudacxx: CUDA C++ standard library (atomics, barriers, memory)
- cudax: experimental features (memory resources, allocators)
- Tuning policies: per-SM hardware-specific algorithm parameters

Competition optimization vectors mapped to CCCL:
- Output TPS (83% weight): warp_reduce, block_reduce, device_topk
- Input TPS (14% weight): device_scan, block_load, prefetch
- Cache TPS (3% weight): prefix caching strategy patterns
- Memory (0.9 util): pooled/cached/buddy allocators

Source: https://github.com/NVIDIA/cccl (shallow clone, HEAD only)
License: Apache-2.0

cccl_upstream/cudax/test/stf/hash/logical_data.cu

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of CUDASTF in CUDA C++ Core Libraries,
+// under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+// SPDX-FileCopyrightText: Copyright (c) 2022-2024 NVIDIA CORPORATION & AFFILIATES.
+//
+//===----------------------------------------------------------------------===//
+
+#include <cuda/experimental/__stf/graph/graph_ctx.cuh>
+#include <cuda/experimental/__stf/stream/stream_ctx.cuh>
+
+using namespace cuda::experimental::stf;
+
+template <typename S>
+__global__ void inc_kernel(S sA)
+{
+  sA(threadIdx.x)++;
+}
+
+template <typename Ctx>
+void run()
+{
+  int A[10] = {0};
+  stream_ctx ctx;
+
+  auto l = ctx.logical_data(A);
+
+  for (size_t k = 0; k < 10; k++)
+  {
+    // size_t h = l.hash();
+    // fprintf(stderr, "iter %zu : logical data hash %zu ctx.hash %zu\n", k, h, ctx.hash());
+
+    ctx.task(l.rw())->*[](cudaStream_t stream, auto sA) {
+      inc_kernel<<<1, 10, 0, stream>>>(sA);
+    };
+  }
+
+  ctx.host_launch(l.read())->*[&](auto /*unused*/) {
+    // fprintf(stderr, "HOST end : logical data hash %zu ctx.hash %zu\n", l.hash(), ctx.hash());
+  };
+
+  ctx.finalize();
+}
+
+int main()
+{
+  run<stream_ctx>();
+  run<graph_ctx>();
+}