ci: skip container builds for documentation changes

[castrojo]

Summary

Skip expensive container builds when only documentation files are changed, reducing CI time and GitHub Actions usage.

Problem

Currently, every change triggers a full container build (~5-10 minutes), even when only editing markdown documentation files. This wastes CI resources and delays doc-only PR merges.

Solution

Add paths-ignore filters to the build workflow to skip builds when only these files change:

• *.md - All markdown files (README.md, AGENTS.md, etc.)
• LICENSE - License file
• .gitignore - Git configuration

What Still Triggers Builds ✓

• Containerfile changes
• system_files/** changes
• Justfile or **.just changes
• bluefin-branding submodule updates
• Workflow file changes
• Manual triggers (workflow_dispatch)
• Merge queue triggers

Benefits

• ✅ Faster PR merges for documentation
• ✅ Reduced GitHub Actions minutes
• ✅ No unnecessary container image pushes
• ✅ Follows same pattern as validate-just.yml
• ✅ Consistent with industry best practices

Testing

This PR itself only changes the workflow file, so it will trigger a build (as expected). Future documentation PRs will skip the build.

To verify:

1. Merge this PR
2. Create a test PR that only modifies README.md
3. Observe that the build workflow is skipped

References

• GitHub Actions docs: Workflow syntax - on.<push|pull_request>.paths
• Follows pattern from validate-just.yml and validate-brewfiles.yaml

[gemini-code-assist]

Note

Gemini is unable to generate a review for this pull request due to the file types involved not being currently supported.

[dosubot]

Related Documentation

Checked 8 published document(s) in 0 knowledge base(s). No updates required.

^{How did I do? Any feedback?}  

[tulilirockz]

This will also skip the MOTD stuff but whatever