[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/thrust/internal/test/thrust.example.summary_statistics.filecheck

@@ -0,0 +1,10 @@
+     CHECK: ******Summary Statistics Example*****
+CHECK-NEXT: The data: 4 7 13 16
+CHECK-NEXT: Count              : 4
+CHECK-NEXT: Minimum            : 4
+CHECK-NEXT: Maximum            : 16
+CHECK-NEXT: Mean               : 10
+CHECK-NEXT: Variance           : 30
+CHECK-NEXT: Standard Deviation : 4.74342
+CHECK-NEXT: Skewness           : 0
+CHECK-NEXT: Kurtosis           : 1.36