.github/workflows: Migrate workflows to Blacksmith runners

[blacksmith-staging]

To whomever may be reviewing this PR,

Blacksmith is the fastest way to run your GitHub Actions.

What does this PR change?

This PR has been automatically generated by a team member in your GitHub organization using Blacksmith's Migration Wizard, or MigWiz for short. This PR changes the following:

1. Your selected workflows will now run on Blacksmith's 2x faster hardware (e.g., runs-on: blacksmith-4vcpu-ubuntu-2204). Learn more about the different instances available to choose from.
2. Your jobs running on Blacksmith will now have all official GitHub and popular third-party cache actions automatically interact with our 4x faster, colocated cache. Learn more about Blacksmith's actions cache.
3. Your GitHub Actions will now actually be observable. Learn more about Blacksmith's logging and other observability features.
4. Your Docker builds will now automatically share their Docker layer cache, resulting in up to 40x faster builds. Learn more about Blacksmith's Docker layer caching.

FAQ

• Is this free? The first 3,000 minutes per month are free.
• Who uses Blacksmith? Clerk, Ashby, VEED, and 600+ others.
• What's the catch? There is none. Merge this thing already.

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• Autofix CI and bot reviews

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• Autofix CI and bot reviews (Staging)

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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^{Reviewed by Cursor Bugbot for commit f2a4d4c. Configure here.}

[cursor]

Matrix inconsistently migrates Windows but not Ubuntu runner

Medium Severity

The test job matrix was changed from [ubuntu-latest, macos-latest, windows-latest] to [ubuntu-latest, macos-latest, blacksmith-4vcpu-windows-2025], migrating only the Windows runner to Blacksmith while leaving ubuntu-latest unmigrated. Every other Ubuntu job in this file and across all other workflow files was migrated to blacksmith-4vcpu-ubuntu-2404. This inconsistency means the matrix mixes GitHub-hosted and Blacksmith runners in a way that doesn't match the PR's intent of full migration, and likely represents an oversight by the auto-migration tool.

 

^{Reviewed by Cursor Bugbot for commit f2a4d4c. Configure here.}

[cursor]

Missing required setup step for Blacksmith Docker build action

High Severity

useblacksmith/build-push-action@v2 requires a preceding useblacksmith/setup-docker-builder@v1 step to handle buildkit and stickydisk management. In v2, this setup logic was extracted into a separate action, so using build-push-action@v2 without first running setup-docker-builder will cause the Docker build to fail. The original docker/build-push-action@v6.5.0 had no such prerequisite, so this is a regression introduced by the migration.

 

^{Reviewed by Cursor Bugbot for commit f2a4d4c. Configure here.}