.github/workflows: Migrate workflows to Blacksmith runners

[blacksmith-sh]

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.

[mesa-dot-dev]

Mesa Description

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.

^{Description generated by Mesa. Update settings}

[mesa-dot-dev]

Performed full review of 809e26f...2f14aad

Analysis

1. Moving to self-hosted runners prevents CI jobs from running on public forks, impacting contributor workflow
2. Trust boundaries for sensitive operations (e.g., release publishing) shift to Blacksmith infrastructure
3. No fallback mechanism to GitHub-hosted runners if self-hosted infrastructure fails
4. Missing documentation for contributors about new self-hosted runner requirements

Tip

Help

Slash Commands:

• /review - Request a full code review
• /review latest - Review only changes since the last review
• /describe - Generate PR description. This will update the PR body or issue comment depending on your configuration
• /help - Get help with Mesa commands and configuration options

^{3 files reviewed | 1 comments | Edit Agent Settings • Read Docs}

[mesa-dot-dev]

Switching this job to a private blacksmith-* runner removes the ability for forked pull requests to run the lint workflow. GitHub does not allow public forks to target self-hosted runners, so external contributions will now queue forever or be skipped, which means we lose CI signal before merging. Could we keep ubuntu-latest (or provide a GitHub-hosted fallback via a matrix) so community PRs still get lint coverage?

 • 

Prompt for Agent

Task: Address review feedback left on GitHub.
Repository: mesa-dot-dev/gitfs#39
File: .github/workflows/python-lint.yml#L16
Action: Open this file location in your editor, inspect the highlighted code, and resolve the issue described below.

Feedback:
Switching this job to a private `blacksmith-*` runner removes the ability for forked pull requests to run the lint workflow. GitHub does not allow public forks to target self-hosted runners, so external contributions will now queue forever or be skipped, which means we lose CI signal before merging. Could we keep `ubuntu-latest` (or provide a GitHub-hosted fallback via a matrix) so community PRs still get lint coverage?