[ET-VK] Add ANY_STORAGE support to softmax and log_softmax

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK] Buckify parakeet #18062
• [ET-VK][qlinear] Add bias support to q4gsw and dq8ca_q4gsw quantized linear ops #18061
• [ET-VK] Implement missing Vulkan operators for Parakeet TDT model #18059
• [ET-VK] Add ANY_STORAGE support to argmax and argmin #18058
• [ET-VK] Add ANY_STORAGE support to embedding #18057
• [ET-VK] Add ANY_STORAGE support to repeat #18056
• [ET-VK] Add ANY_STORAGE support to native_layer_norm #18055
• -> [ET-VK] Add ANY_STORAGE support to softmax and log_softmax #18054
• [ET-VK] Add ANY_STORAGE support to expand_copy #18053
• [ET-VK] Add ANY_STORAGE support to arange and full #18052
• [ET-VK] Generalize constant_pad_nd to support any storage type and packed dimension #18051
• [ET-VK] Add symint infrastructure to VulkanBackend and ComputeGraph #18050
• [ET-VK] Add Vulkan backend support for Parakeet runner and export #18049
• [ET-VK][ez] Fix IndexError in Vulkan partitioner DtypeSetList/TensorRepSetList #18048
• [ET-VK] Fix exponential blowup in tag_memory_meta_pass repset tracing #18207

Add a buffer shader variant for softmax using workgroup-based reduction with
shared memory. The buffer shader dispatches one workgroup per "row" along the
reduction dimension, with NWORKERS=4 threads per workgroup cooperating on the
max and sum reductions before writing outputs.

In Softmax.cpp, the existing texture dispatch is renamed add_softmax_texture_node
and new add_softmax_buffer_node / add_softmax_node dispatch functions are added.
op_registry.py is updated from ANY_TEXTURE to ANY_STORAGE so the partitioner
accepts buffer-storage inputs. Test cases now also exercise buffer storage.

Differential Revision: D95970171

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/18054

• 📄 Preview Python docs built from this PR

Note: Links to docs will display an error until the docs builds have been completed.

❌ 2 New Failures, 11 Cancelled Jobs, 1 Unrelated Failure

As of commit 0ac4c10 with merge base 22174fa ():

NEW FAILURES - The following jobs have failed:

• pull / test-multimodal-linux (gemma3-4b) / linux-job (gh)
  RuntimeError: Command docker exec -t 6689aba520810fd0384e675c6e5d4f7050fe73deb5e7b498ae4b60caebeeecaf /exec failed with exit code 139
• pull / unittest-editable / macos / macos-job (gh)
  backends/xnnpack/test/ops/test_conv2d.py::TestConv2d::test_fp16_conv2d

CANCELLED JOBS - The following jobs were cancelled. Please retry:

• Test Metal Backend / export-model-metal-artifact (mistralai, Voxtral-Mini-3B-2507, non-quantized) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (mistralai, Voxtral-Mini-3B-2507, quantized-int4-metal) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (mistralai, Voxtral-Mini-4B-Realtime-2602, quantized-int4-metal) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (nvidia, parakeet-tdt, non-quantized) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (nvidia, parakeet-tdt, quantized-int4-metal) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (openai, whisper-large-v3-turbo, non-quantized) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (openai, whisper-large-v3-turbo, quantized-int4-metal) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (openai, whisper-small, non-quantized) / macos-job (gh)
• Test Metal Backend / export-model-metal-artifact (openai, whisper-small, quantized-int4-metal) / macos-job (gh)
• Test Metal Backend / test-executorch-metal-build / macos-job (gh)
• Test Metal Backend / test-metal-backend-modules / macos-job (gh)

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / test-moshi-linux / linux-job (gh) (matched linux rule in flaky-rules.json)
  E: Failed to fetch http://security.ubuntu.com/ubuntu/pool/main/libs/libssh/libssh-gcrypt-4_0.9.6-2ubuntu0.22.04.6_amd64.deb 404 Not Found [IP: 185.125.190.82 80]

This comment was automatically generated by Dr. CI and updates every 15 minutes.

[github-actions]

This PR needs a release notes: label

If your change should be included in the release notes (i.e. would users of this library care about this change?), please use a label starting with release notes:. This helps us keep track and include your important work in the next release notes.

To add a label, you can comment to pytorchbot, for example
@pytorchbot label "release notes: none"

For more information, see
https://github.com/pytorch/pytorch/wiki/PyTorch-AutoLabel-Bot#why-categorize-for-release-notes-and-how-does-it-work.