[ET-VK][runtime][3/3] Enforce device-safe dispatch geometry

[SS-JIA]

Stack from ghstack (oldest at bottom):

• [ET-VK][ops] Add batch support to q8ta convolutions #22254
• -> [ET-VK][runtime][3/3] Enforce device-safe dispatch geometry #22225
• [ET-VK][runtime][2/3] Add typed dispatch size abstractions #22224
• [ET-VK][runtime][1/3] Prepare linear shaders for 2D dispatch #22223
• [ET-VK][ops] Move group norm reduction lanes to Z #22222

Migrate dispatch, prepack, profiling, and workgroup picker interfaces to
GlobalWorkGrid and LocalWorkGroup. Wrap oversized linear grids using device
limits and validate final geometry before vkCmdDispatch.

Carry exact local geometry as GlobalWorkGrid metadata. Cooperative and
reduction grid pickers set it explicitly, while pick_required_lwg validates
and returns it. Preserve elongated Conv1d depthwise workgroups where the
default shape would regress GPU latency. Add end-to-end oversized linear
dispatch coverage.

Authored with Codex.

Differential Revision: D117706355

[pytorch-bot]

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❌ 2 New Failures, 1 Unrelated Failure

As of commit a745e5e with merge base a5f15b5 ():

NEW FAILURES - The following jobs have failed:

• pull / test-llama-runner-linux (fp32, xnnpack+custom+qe, linux.2xlarge, executorch-ubuntu-22.04-clang12) / linux-job (gh)
  RuntimeError: Command docker exec -t d9bfbb65cf7a4260da61d534d5a70a307c29e404862f50c71494df44dba3c0ff /exec failed with exit code 1
• pull / test-llama-runner-linux (fp32, xnnpack+custom+quantize_kv, linux.2xlarge, executorch-ubuntu-22.04... / linux-job (gh)
  RuntimeError: Command docker exec -t 1583553466c694c2374567b68ecaa632e141b0064159c2b85f8d3532a3d961b6 /exec failed with exit code 1

BROKEN TRUNK - The following job failed but were present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / test-qnn-testsuite-linux / test-backend-linux (qnn, models) / linux-job (gh) (trunk failure)
  The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.

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