Add ARM CI Jobs

[Wesley Wigham (weswigham)]

Add some ARM CI jobs so we catch ARM-specific test failures.

[Copilot]

🟡 Changes recommended

Both new jobs still select x64 runner labels, so no ARM64 tests execute.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Adds ARM64 CI coverage for Linux and Windows.

Changes:

• Adds ARM64 entries to the test matrix.
• Retains coverage and merge-group behavior.

File summaries

File	Description
.github/workflows/ci.yml	Adds Linux and Windows ARM64 test configurations.

Review details

Suppressed comments (1)

.github/workflows/ci.yml:103

• This also selects an x64 host because runs-on uses matrix.config.runner, while arch is otherwise unused. Set the Windows ARM runner label directly so the matrix actually exercises ARM64.

          - runner: windows-latest
            os: windows
            arch: arm64

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Balanced

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[Copilot]

🟡 Changes recommended

ARM jobs can collide with existing baseline artifact names during concurrent failures.

Get a fresh assessment by requesting another Copilot review.

Review details

Suppressed comments (1)

.github/workflows/ci.yml:103

• This ARM entry falls back to matrix.config.os for failed-test artifacts, producing windows-new-baselines, which is already used by the x64 Windows job. Concurrent failures therefore make one immutable artifact upload conflict and discard that job's baselines. Assign a unique matrix name here.

          - runner: windows-11-arm
            os: windows
            coverage: true
            skip: ${{ github.event_name == 'merge_group' }}

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Balanced

[Copilot]

🟢 Approval recommended

The runner labels are valid and the new matrix entries correctly reuse the existing test workflow.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[Jake Bailey (jakebailey)]

This seems fine, but didn't expose any problems, and I am at least moderately concerned about the capacity here. Hopefully they have enough, unlike macOS.

[Wesley Wigham (weswigham)]

They completed before the osx runner I think, so I think they're worth having. Also, looking at the CI results, they're actually faster than the x86 test runners - go figure. (And linux arm runners are even billed at a cheaper rate than x64, apparently.)