ci: pin ut-a2a3 to the x86 (X64) self-hosted runner

[ChaoWao]

What

Pin ut-a2a3 to the x86 (X64) self-hosted runner.

Why

The a2a3 runner pool is mixed-arch:

• x86 8P: infra-gpu-npu-021[-2] (label X64)
• arm64 4P: runner-dev4-7 / runner-dev8-11 (label ARM64)

runs-on: [self-hosted, a2a3] can land ut-a2a3 on a 4-NPU arm64 box, but the job assumes the 8-NPU x86 host — DEVICE_RANGE is 0-7/8-15, and the local pto-isa mirror (which makes the build's pto-isa clone reliable behind the pod proxy) only exists there. Adding the X64 label targets it deterministically.

This PR is also the validation run for that pto-isa local-mirror setup — the Set up environment step (the pto-isa clone) should now succeed.

🤖 Generated with Claude Code

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Note

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 1bd476e5-516d-4621-994f-043d81aaf454

📥 Commits

Reviewing files that changed from the base of the PR and between a756969 and 74a3164.

📒 Files selected for processing (1)

• .github/workflows/ci.yml

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📝 Walkthrough

Walkthrough

The ut-a2a3 CI job now targets only self-hosted a2a3 runners labeled X64, with comments documenting the pool’s x86_64 and arm64 host mix.

Changes

CI runner targeting

Layer / File(s)	Summary
Pin ut-a2a3 to X64 runners .github/workflows/ci.yml	The job’s runs-on labels now include X64, and comments explain why arm64 runners are excluded.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related PRs

• hw-native-sys/simpler#1356: Also changes the ut-a2a3 CI workload configuration.
• hw-native-sys/simpler#1360: Also adjusts architecture-aware ut-a2a3 runner behavior.
• hw-native-sys/simpler#1361: Also modifies A2A3 CI behavior for X64 and ARM64 hosts.

Poem

A rabbit hops where X64 runners gleam,
A2A3 now follows a focused dream.
No arm64 detour, no wandering track,
The unit tests bound to the right host stack.
“Hop hop hooray!” says the CI hare.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: pinning the ut-a2a3 CI job to the x86 X64 self-hosted runner.
Description check	✅ Passed	The description is directly related to the change and explains the runner pinning and why it is needed.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[ChaoWao]

Closing as test-only.

The actual fix lives on the runner, not in this repo: a2-github-ci (infra-gpu-npu-021) now hosts a local pto-isa mirror with a url.insteadOf redirect, so the build's git clone of pto-isa resolves to a same-FS hardlink clone (~20 ms) instead of going through the pod proxy — which was dropping the HTTP/2 pack with curl 56 GnuTLS recv error / early EOF. (pto-isa is only ~17 MB; the failure was the proxy, not size.)

This PR's ut-a2a3 run validated it: green on infra-gpu-npu-021-2 (the same runner that failed in #1267), pto-isa clone step passed.

The X64 label pin here is optional hardening — it keeps ut-a2a3 off the arm64 4P runners (which have no mirror). Happy to re-send as a real change if we want that pin permanent.