feat(cccl): integrate missing CCCL directories — python/, ci/, .agent/, docs/, test/

Sparse-checkout from NVIDIA/cccl main branch to complete cccl_upstream:

Added:
- python/cuda_cccl/ (226 files) — Python bindings for device-level algorithms
  Critical for muh toolchain: cuda.compute.reduce_into, scan, radix_sort, etc.
  Includes 204 .py files with full test coverage for all 27 algorithms
- ci/ (163 files) — Build/test infrastructure
  build_cub.sh, test_cub.sh, build_and_test_targets.sh, matrix.yaml
  Directly maps to our [INFRA-CI] and [INFRA-BUILD] items
- .agent/skills/ (7 files) — NVIDIA's own agent skills for CCCL
  cccl-style/SKILL.md, cccl-test/SKILL.md, sass-diff/SKILL.md
- docs/ (491 files) — Official CCCL documentation
  CI references, CMake guides, Python compute docs, libcudacxx PTX docs
- test/ (12 files) — Top-level integration tests (cuda_smoke, stdpar)
- Root configs: .clang-format, .clang-tidy, CONTRIBUTING.md, pyproject.toml
- CLAUDE.md symlink → AGENTS.md (NVIDIA's standard)

cccl_upstream now mirrors full NVIDIA/cccl structure:
  Before: 42M (cub + thrust + libcudacxx + cudax + c + examples + benchmarks)
  After:  53M (+python +ci +docs +.agent +test +configs)

This completes the CCCL base needed for:
- [muh-bench] items: ci/util/build_and_test_targets.sh for targeted builds
- [CCCL-verify] items: python/cuda_cccl/tests/ as reference implementations
- [CCCL-test] items: ci/test_cub.sh, ci/test_thrust.sh
- Agent workflow: .agent/skills/ for consistent style and test patterns

cccl_upstream/docs/thrust/algorithms/copying.rst

@@ -0,0 +1,12 @@
+.. _thrust-module-api-algorithms-copying:
+
+Copying
+-------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   copying/gather
+   copying/scatter
+   ../api/group__copying*

cccl_upstream/docs/thrust/algorithms/copying/gather.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-copying-gather:
+
+Gather
+^^^^^^^
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__gather*

cccl_upstream/docs/thrust/algorithms/copying/scatter.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-copying-scatter:
+
+Scatter
+^^^^^^^
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__scatter*

cccl_upstream/docs/thrust/algorithms/merging.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-merging:
+
+Merging
+-------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../api/group__merging*

cccl_upstream/docs/thrust/algorithms/prefix_sum.rst

@@ -0,0 +1,12 @@
+.. _thrust-module-api-algorithms-prefix_sums:
+
+Prefix sums
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   prefix_sums/segmented
+   prefix_sums/transformed
+   ../api/group__prefixsums*

cccl_upstream/docs/thrust/algorithms/prefix_sums/segmented.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-prefix_sums-segmented:
+
+Segmented Prefix Sums
+----------------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__segmentedprefix*

cccl_upstream/docs/thrust/algorithms/prefix_sums/transformed.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-prefix_sums-transformed:
+
+Transformed Prefix Sums
+-------------------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__transformed__prefixsums*

cccl_upstream/docs/thrust/algorithms/reductions.rst

@@ -0,0 +1,16 @@
+.. _thrust-module-api-algorithms-reductions:
+
+Reductions
+----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   reductions/comparisons
+   reductions/counting
+   reductions/extrema
+   reductions/logical
+   reductions/predicates
+   reductions/transformed
+   ../api/group__reductions*

cccl_upstream/docs/thrust/algorithms/reductions/comparisons.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-comparisons:
+
+Comparisons
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__comparisons*

cccl_upstream/docs/thrust/algorithms/reductions/counting.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-counting:
+
+Counting
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__counting*

cccl_upstream/docs/thrust/algorithms/reductions/extrema.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-extrema:
+
+Extrema
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__extrema*

cccl_upstream/docs/thrust/algorithms/reductions/logical.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-logical:
+
+Logical
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__logical*

cccl_upstream/docs/thrust/algorithms/reductions/predicates.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-predicates:
+
+Predicates
+-----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__predicates*

cccl_upstream/docs/thrust/algorithms/reductions/transformed.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reductions-transformed:
+
+Transformed Reductions
+----------------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__transformed__reductions*

cccl_upstream/docs/thrust/algorithms/reordering.rst

@@ -0,0 +1,12 @@
+.. _thrust-module-api-algorithms-reordering:
+
+Reordering
+----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   reordering/partitioning
+   reordering/shuffling
+   reordering/stream_compaction

cccl_upstream/docs/thrust/algorithms/reordering/partitioning.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reordering-partitioning:
+
+Partitioning
+-------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__partitioning*

cccl_upstream/docs/thrust/algorithms/reordering/shuffling.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reordering-shuffling:
+
+Shuffling
+-------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__shuffling*

cccl_upstream/docs/thrust/algorithms/reordering/stream_compaction.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-reordering-stream-compactation:
+
+Stream Compactation
+-------------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__stream__compaction*

cccl_upstream/docs/thrust/algorithms/searching.rst

@@ -0,0 +1,11 @@
+.. _thrust-module-api-algorithms-searching:
+
+Searching
+----------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   searching/binary_search
+   ../api/group__searching*

cccl_upstream/docs/thrust/algorithms/searching/binary_search.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-searching-binary-search:
+
+Binary Search
+--------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__binary__search*

cccl_upstream/docs/thrust/algorithms/set_operations.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-set-operations:
+
+Set Operations
+---------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../api/group__set__operations*

cccl_upstream/docs/thrust/algorithms/sorting.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-sorting:
+
+Sorting
+--------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../api/group__sorting*

cccl_upstream/docs/thrust/algorithms/transformations.rst

@@ -0,0 +1,13 @@
+.. _thrust-module-api-algorithms-transformations:
+
+Transformations
+-----------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   transformations/filling
+   transformations/modifying
+   transformations/replacing
+   ../api/group__transformations*

cccl_upstream/docs/thrust/algorithms/transformations/filling.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-transformations-filling:
+
+Filling
+--------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__filling*

cccl_upstream/docs/thrust/algorithms/transformations/modifying.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-transformations-modifying:
+
+Modifying
+--------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__modifying*

cccl_upstream/docs/thrust/algorithms/transformations/replacing.rst

@@ -0,0 +1,10 @@
+.. _thrust-module-api-algorithms-transformations-replacing:
+
+Replacing
+--------------
+
+.. toctree::
+   :glob:
+   :maxdepth: 1
+
+   ../../api/group__replacing*