Add Claude Code GitHub Workflow

[dguido]

🤖 Installing Claude Code GitHub App

This PR adds a GitHub Actions workflow that enables Claude Code integration in our repository.

What is Claude Code?

Claude Code is an AI coding agent that can help with:

• Bug fixes and improvements
• Documentation updates
• Implementing new features
• Code reviews and suggestions
• Writing tests
• And more!

How it works

Once this PR is merged, we'll be able to interact with Claude by mentioning @claude in a pull request or issue comment.
Once the workflow is triggered, Claude will analyze the comment and surrounding context, and execute on the request in a GitHub action.

Important Notes

• This workflow won't take effect until this PR is merged
• @claude mentions won't work until after the merge is complete
• The workflow runs automatically whenever Claude is mentioned in PR or issue comments
• Claude gets access to the entire PR or issue context including files, diffs, and previous comments

Security

• Our Anthropic API key is securely stored as a GitHub Actions secret
• Only users with write access to the repository can trigger the workflow
• All Claude runs are stored in the GitHub Actions run history
• Claude's default tools are limited to reading/writing files and interacting with our repo by creating comments, branches, and commits.
• We can add more allowed tools by adding them to the workflow file like:

allowed_tools: Bash(npm install),Bash(npm run build),Bash(npm run lint),Bash(npm run test)

There's more information in the Claude Code documentation.

After merging this PR, let's try mentioning @claude in a comment on any PR to get started!

[michaelbrownuc]

We haven't made this mirror AI/bystander-proof yet. While it should not be possible for anyone or AI to mess with the deployed version of Buttercup that is currently competing in the AFC, we do have a lot of deployment code in here that puts the competititon at risk. Before merging this workflow we need to do some manual cleanup now the we are "pencils down" on Buttercup to make it standalone from the competition. This should be done early next week, but at the latest we can merge this on July 11 without it because the final scored round will be closed.