[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/libcudacxx/test/debugging/array/gdb.expected

@@ -0,0 +1,44 @@
+=============== array.normal begin ===============
+cuda::std::array<int, 3> = {
+  [0] = -7,
+  [1] = 0,
+  [2] = 42
+}
+=============== array.normal end ===============
+=============== array.empty begin ===============
+cuda::std::array<int, 0>
+=============== array.empty end ===============
+=============== array.nested begin ===============
+cuda::std::array<cuda::std::array<int, 2>, 2> = {
+  [0] = cuda::std::array<int, 2> = {
+    [0] = 13,
+    [1] = -5
+  },
+  [1] = cuda::std::array<int, 2> = {
+    [0] = 0,
+    [1] = 88
+  }
+}
+=============== array.nested end ===============
+=============== array.alias begin ===============
+cuda::std::array<int, 4> = {
+  [0] = -31,
+  [1] = 17,
+  [2] = 8,
+  [3] = -64
+}
+=============== array.alias end ===============
+=============== array.update.before begin ===============
+cuda::std::array<int, 3> = {
+  [0] = 6,
+  [1] = -91,
+  [2] = 52
+}
+=============== array.update.before end ===============
+=============== array.update.after begin ===============
+cuda::std::array<int, 3> = {
+  [0] = 3,
+  [1] = 85,
+  [2] = -12
+}
+=============== array.update.after end ===============